import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
        return hasNextByte();
    }

    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException();
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }
}

public class Main {
    static int MOD = 1000000007;

    static int C(int n, int r) {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    }

    public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }

    static long lcm(long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    }

    static long f(long n, Map<Long, Long> map) {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    }

    public static long factorial(long n) {
        return n <= 0 ? 1 : n * factorial(n - 1);
    }

    private static long calcLCM(long val1, long val2) {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    }

    static String nextPermutation(String s) {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    }

    public List<String> permutation(List<String> list, String target, String ans) {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    }

    public static int lowerbound(int[] a, int key) {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int upperbound(int[] a, int key) {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int count(int[] a, int key) {
        return upperbound(a, key) - lowerbound(a, key);
    }

    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    }

} import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.util.ArrayList; ArrayList java.util import java.util.Collections; Collections java.util import java.util.List; List java.util import java.util.Map; Map java.util import java.util.NoSuchElementException; NoSuchElementException java.util class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
        return hasNextByte();
    }

    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException();
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }
} FastScanner private final InputStream in = System.in; in System.in System System.in private final byte[] buffer = new byte[1024]; buffer new byte[1024] 1024 private int ptr = 0; ptr 0 private int buflen = 0; buflen 0 private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    } hasNextByte {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    } if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        } ptr < buflen ptr buflen {
            return true;
        } return true; true {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        } ptr = 0 ptr 0 try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                buflen = in.read(buffer);
            } buflen = in.read(buffer) buflen in.read(buffer) in.read in buffer if (buflen <= 0) {
                return false;
            } buflen <= 0 buflen 0 {
                return false;
            } return false; false return true; true private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    } readByte {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    } if (hasNextByte())
            return buffer[ptr++];
        else
            return -1; hasNextByte() hasNextByte return buffer[ptr++]; buffer[ptr++] buffer ptr++ ptr return -1; -1 1 private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    } isPrintableChar {
        return 33 <= c && c <= 126;
    } return 33 <= c && c <= 126; 33 <= c && c <= 126 33 <= c 33 c c <= 126 c 126 int c c public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
        return hasNextByte();
    } hasNext {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
        return hasNextByte();
    } while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++; hasNextByte() && !isPrintableChar(buffer[ptr]) hasNextByte() hasNextByte !isPrintableChar(buffer[ptr]) isPrintableChar(buffer[ptr]) isPrintableChar buffer[ptr] buffer ptr ptr++ ptr return hasNextByte(); hasNextByte() hasNextByte public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } next {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    } if (!hasNext())
            throw new NoSuchElementException(); !hasNext() hasNext() hasNext throw new NoSuchElementException(); new NoSuchElementException() StringBuilder sb = new StringBuilder(); sb new StringBuilder() int b = readByte(); b readByte() readByte while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        } isPrintableChar(b) isPrintableChar b {
            sb.appendCodePoint(b);
            b = readByte();
        } sb.appendCodePoint(b) sb.appendCodePoint sb b b = readByte() b readByte() readByte return sb.toString(); sb.toString() sb.toString sb public long nextLong() {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } nextLong {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    } if (!hasNext())
            throw new NoSuchElementException(); !hasNext() hasNext() hasNext throw new NoSuchElementException(); new NoSuchElementException() long n = 0; n 0 boolean minus = false; minus false int b = readByte(); b readByte() readByte if (b == '-') {
            minus = true;
            b = readByte();
        } b == '-' b '-' {
            minus = true;
            b = readByte();
        } minus = true minus true b = readByte() b readByte() readByte if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        } b < '0' || '9' < b b < '0' b '0' '9' < b '9' b {
            throw new NumberFormatException();
        } throw new NumberFormatException(); new NumberFormatException() while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        } true {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        } if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            } '0' <= b && b <= '9' '0' <= b '0' b b <= '9' b '9' {
                n *= 10;
                n += b - '0';
            } n *= 10 n 10 n += b - '0' n b - '0' b '0' if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            } b == -1 || !isPrintableChar(b) b == -1 b -1 1 !isPrintableChar(b) isPrintableChar(b) isPrintableChar b {
                return minus ? -n : n;
            } return minus ? -n : n; minus ? -n : n minus -n n n {
                throw new NumberFormatException();
            } throw new NumberFormatException(); new NumberFormatException() b = readByte() b readByte() readByte public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException();
        return (int) nl;
    } nextInt {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException();
        return (int) nl;
    } long nl = nextLong(); nl nextLong() nextLong if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException(); nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE nl < Integer.MIN_VALUE nl Integer.MIN_VALUE Integer Integer.MIN_VALUE nl > Integer.MAX_VALUE nl Integer.MAX_VALUE Integer Integer.MAX_VALUE throw new NumberFormatException(); new NumberFormatException() return (int) nl; (int) nl public double nextDouble() {
        return Double.parseDouble(next());
    } nextDouble {
        return Double.parseDouble(next());
    } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next public class Main {
    static int MOD = 1000000007;

    static int C(int n, int r) {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    }

    public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }

    static long lcm(long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    }

    static long f(long n, Map<Long, Long> map) {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    }

    public static long factorial(long n) {
        return n <= 0 ? 1 : n * factorial(n - 1);
    }

    private static long calcLCM(long val1, long val2) {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    }

    static String nextPermutation(String s) {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    }

    public List<String> permutation(List<String> list, String target, String ans) {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    }

    public static int lowerbound(int[] a, int key) {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int upperbound(int[] a, int key) {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int count(int[] a, int key) {
        return upperbound(a, key) - lowerbound(a, key);
    }

    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    }

} Main static int MOD = 1000000007; MOD 1000000007 static int C(int n, int r) {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    } C {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    } int num = 1; num 1 for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        } int i = 1; int i = 1; i 1 i <= r i r i++ i++ i {
            num = num * (n - i + 1) / i;
        } {
            num = num * (n - i + 1) / i;
        } num = num * (n - i + 1) / i num num * (n - i + 1) / i num * (n - i + 1) num (n - i + 1) n - i n i 1 i return num; num int n n int r r public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    } gcd {
        return b == 0 ? a : gcd(b, a % b);
    } return b == 0 ? a : gcd(b, a % b); b == 0 ? a : gcd(b, a % b) b == 0 b 0 a gcd(b, a % b) gcd b a % b a b int a a int b b static long lcm(long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    } lcm {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    } long temp; temp long c = a; c a c *= b c b while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        } (temp = a % b) != 0 (temp = a % b) temp a % b a b 0 {
            a = b;
            b = temp;
        } a = b a b b = temp b temp return (long) (c / b); (long) (c / b) c b long a a long b b static long f(long n, Map<Long, Long> map) {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    } f {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    } if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        } n < 2 n 2 return 1; 1 if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        } map.containsKey(n) map.containsKey map n {
            return map.get(n);
        } return map.get(n); map.get(n) map.get map n {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        } map.put(n, n * f(n - 2, map)) map.put map n n * f(n - 2, map) n f(n - 2, map) f n - 2 n 2 map return map.get(n); map.get(n) map.get map n long n n Map<Long, Long> map map public static long factorial(long n) {
        return n <= 0 ? 1 : n * factorial(n - 1);
    } factorial {
        return n <= 0 ? 1 : n * factorial(n - 1);
    } return n <= 0 ? 1 : n * factorial(n - 1); n <= 0 ? 1 : n * factorial(n - 1) n <= 0 n 0 1 n * factorial(n - 1) n factorial(n - 1) factorial n - 1 n 1 long n n private static long calcLCM(long val1, long val2) {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    } calcLCM {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    } long maxValue = Math.max(val1, val2); maxValue Math.max(val1, val2) Math.max Math val1 val2 long minValue = Math.min(val1, val2); minValue Math.min(val1, val2) Math.min Math val1 val2 long val3 = maxValue * minValue; val3 maxValue * minValue maxValue minValue if (minValue == 0)
            return maxValue; minValue == 0 minValue 0 return maxValue; maxValue long temp; temp while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        } (temp = maxValue % minValue) != 0 (temp = maxValue % minValue) temp maxValue % minValue maxValue minValue 0 {
            maxValue = minValue;
            minValue = temp;
        } maxValue = minValue maxValue minValue minValue = temp minValue temp return (long) (val3 / minValue); (long) (val3 / minValue) val3 minValue long val1 val1 long val2 val2 static String nextPermutation(String s) {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    } nextPermutation {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    } ArrayList<Character> list = new ArrayList<>(); list new ArrayList<>() for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i)); int i = 0; int i = 0; i 0 i < s.length() i s.length() s.length s i++ i++ i list.add(s.charAt(i)); list.add(s.charAt(i)) list.add list s.charAt(i) s.charAt s i int pivotPos = -1; pivotPos -1 1 char pivot = 0; pivot 0 for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        } int i = list.size() - 2; int i = list.size() - 2; i list.size() - 2 list.size() list.size list 2 i >= 0 i 0 i-- i-- i {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        } {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        } if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            } list.get(i) < list.get(i + 1) list.get(i) list.get list i list.get(i + 1) list.get list i + 1 i 1 {
                pivotPos = i;
                pivot = list.get(i);
                break;
            } pivotPos = i pivotPos i pivot = list.get(i) pivot list.get(i) list.get list i break; if (pivotPos == -1 && pivot == 0)
            return "Final"; pivotPos == -1 && pivot == 0 pivotPos == -1 pivotPos -1 1 pivot == 0 pivot 0 return "Final"; "Final" int L = pivotPos + 1 L pivotPos + 1 pivotPos 1 R = list.size() - 1; R list.size() - 1 list.size() list.size list 1 int minPos = -1; minPos -1 1 char min = Character.MAX_VALUE; min Character.MAX_VALUE Character Character.MAX_VALUE for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        } int i = R; int i = R; i R i >= L i L i-- i-- i {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        } {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        } if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            } pivot < list.get(i) pivot list.get(i) list.get list i {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            } if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                } list.get(i) < min list.get(i) list.get list i min {
                    min = list.get(i);
                    minPos = i;
                } min = list.get(i) min list.get(i) list.get list i minPos = i minPos i Collections.swap(list, pivotPos, minPos) Collections.swap Collections list pivotPos minPos Collections.sort(list.subList(L, R + 1)) Collections.sort Collections list.subList(L, R + 1) list.subList list L R + 1 R 1 StringBuilder sb = new StringBuilder(); sb new StringBuilder() for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i)); int i = 0; int i = 0; i 0 i < list.size() i list.size() list.size list i++ i++ i sb.append(list.get(i)); sb.append(list.get(i)) sb.append sb list.get(i) list.get list i return sb.toString(); sb.toString() sb.toString sb String s s public List<String> permutation(List<String> list, String target, String ans) {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    } permutation {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    } if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        } target.length() <= 1 target.length() target.length target 1 {
            list.add(ans + target);
        } list.add(ans + target) list.add list ans + target ans target {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        } for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            } int i = 0; int i = 0; i 0 i < target.length() i target.length() target.length target i++ i++ i {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            } {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            } permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i)) permutation list target.substring(0, i) + target.substring(i + 1) target.substring(0, i) target.substring target 0 i target.substring(i + 1) target.substring target i + 1 i 1 ans + target.charAt(i) ans target.charAt(i) target.charAt target i return list; list List<String> list list String target target String ans ans public static int lowerbound(int[] a, int key) {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    } lowerbound {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    } if (a[a.length - 1] < key)
            return a.length; a[a.length - 1] < key a[a.length - 1] a a.length - 1 a.length a a.length 1 key return a.length; a.length a a.length int lb = 0 lb 0 ub = a.length - 1 ub a.length - 1 a.length a a.length 1 mid; mid do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub); lb < ub lb ub {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } mid = (ub + lb) / 2 mid (ub + lb) / 2 (ub + lb) ub lb 2 if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid; a[mid] < key a[mid] a mid key lb = mid + 1 lb mid + 1 mid 1 ub = mid ub mid return ub; ub int[] a a int key key public static int upperbound(int[] a, int key) {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    } upperbound {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    } if (a[a.length - 1] <= key)
            return a.length; a[a.length - 1] <= key a[a.length - 1] a a.length - 1 a.length a a.length 1 key return a.length; a.length a a.length int lb = 0 lb 0 ub = a.length - 1 ub a.length - 1 a.length a a.length 1 mid; mid do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub); lb < ub lb ub {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } mid = (ub + lb) / 2 mid (ub + lb) / 2 (ub + lb) ub lb 2 if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid; a[mid] <= key a[mid] a mid key lb = mid + 1 lb mid + 1 mid 1 ub = mid ub mid return ub; ub int[] a a int key key public static int count(int[] a, int key) {
        return upperbound(a, key) - lowerbound(a, key);
    } count {
        return upperbound(a, key) - lowerbound(a, key);
    } return upperbound(a, key) - lowerbound(a, key); upperbound(a, key) - lowerbound(a, key) upperbound(a, key) upperbound a key lowerbound(a, key) lowerbound a key int[] a a int key key public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    } main {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    } FastScanner fs = new FastScanner(); fs new FastScanner() int[][] a = new int[3][3]; a new int[3][3] 3 3 int sum = 0; sum 0 for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        } int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        } {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        } for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            } int j = 0; int j = 0; j 0 j < 3 j 3 j++ j++ j {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            } {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            } a[i][j] = fs.nextInt() a[i][j] a[i] a i j fs.nextInt() fs.nextInt fs sum += a[i][j] sum a[i][j] a[i] a i j System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No") System.out.println System.out System System.out sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No" sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] sum % 3 == 0 sum % 3 sum 3 0 (sum / 3) == a[0][0] + a[1][1] + a[2][2] (sum / 3) sum 3 a[0][0] + a[1][1] + a[2][2] a[0][0] + a[1][1] + a[2][2] a[0][0] a[0] a 0 0 a[1][1] a[1] a 1 1 a[2][2] a[2] a 2 2 "Yes" "No" String[] args args public class Main {
    static int MOD = 1000000007;

    static int C(int n, int r) {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    }

    public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }

    static long lcm(long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    }

    static long f(long n, Map<Long, Long> map) {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    }

    public static long factorial(long n) {
        return n <= 0 ? 1 : n * factorial(n - 1);
    }

    private static long calcLCM(long val1, long val2) {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    }

    static String nextPermutation(String s) {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    }

    public List<String> permutation(List<String> list, String target, String ans) {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    }

    public static int lowerbound(int[] a, int key) {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int upperbound(int[] a, int key) {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int count(int[] a, int key) {
        return upperbound(a, key) - lowerbound(a, key);
    }

    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    }

} public class Main {
    static int MOD = 1000000007;

    static int C(int n, int r) {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    }

    public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }

    static long lcm(long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    }

    static long f(long n, Map<Long, Long> map) {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    }

    public static long factorial(long n) {
        return n <= 0 ? 1 : n * factorial(n - 1);
    }

    private static long calcLCM(long val1, long val2) {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    }

    static String nextPermutation(String s) {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    }

    public List<String> permutation(List<String> list, String target, String ans) {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    }

    public static int lowerbound(int[] a, int key) {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int upperbound(int[] a, int key) {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int count(int[] a, int key) {
        return upperbound(a, key) - lowerbound(a, key);
    }

    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    }

} Main
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

class FastScanner {
    private final InputStream in = System.in;
    private final byte[] buffer = new byte[1024];
    private int ptr = 0;
    private int buflen = 0;

    private boolean hasNextByte() {
        if (ptr < buflen) {
            return true;
        } else {
            ptr = 0;
            try {
                buflen = in.read(buffer);
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (buflen <= 0) {
                return false;
            }
        }
        return true;
    }

    private int readByte() {
        if (hasNextByte())
            return buffer[ptr++];
        else
            return -1;
    }

    private static boolean isPrintableChar(int c) {
        return 33 <= c && c <= 126;
    }

    public boolean hasNext() {
        while (hasNextByte() && !isPrintableChar(buffer[ptr]))
            ptr++;
        return hasNextByte();
    }

    public String next() {
        if (!hasNext())
            throw new NoSuchElementException();
        StringBuilder sb = new StringBuilder();
        int b = readByte();
        while (isPrintableChar(b)) {
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }

    public long nextLong() {
        if (!hasNext())
            throw new NoSuchElementException();
        long n = 0;
        boolean minus = false;
        int b = readByte();
        if (b == '-') {
            minus = true;
            b = readByte();
        }
        if (b < '0' || '9' < b) {
            throw new NumberFormatException();
        }
        while (true) {
            if ('0' <= b && b <= '9') {
                n *= 10;
                n += b - '0';
            } else if (b == -1 || !isPrintableChar(b)) {
                return minus ? -n : n;
            } else {
                throw new NumberFormatException();
            }
            b = readByte();
        }
    }

    public int nextInt() {
        long nl = nextLong();
        if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
            throw new NumberFormatException();
        return (int) nl;
    }

    public double nextDouble() {
        return Double.parseDouble(next());
    }
}

public class Main {
    static int MOD = 1000000007;

    static int C(int n, int r) {
        int num = 1;
        for (int i = 1; i <= r; i++) {
            num = num * (n - i + 1) / i;
        }
        return num;
    }

    public static int gcd(int a, int b) {
        return b == 0 ? a : gcd(b, a % b);
    }

    static long lcm(long a, long b) {
        long temp;
        long c = a;
        c *= b;
        while ((temp = a % b) != 0) {
            a = b;
            b = temp;
        }
        return (long) (c / b);
    }

    static long f(long n, Map<Long, Long> map) {
        if (n < 2)
            return 1;
        else if (map.containsKey(n)) {
            return map.get(n);
        } else {
            map.put(n, n * f(n - 2, map));
            return map.get(n);
        }

    }

    public static long factorial(long n) {
        return n <= 0 ? 1 : n * factorial(n - 1);
    }

    private static long calcLCM(long val1, long val2) {
        long maxValue = Math.max(val1, val2);
        long minValue = Math.min(val1, val2);
        long val3 = maxValue * minValue;

        if (minValue == 0)
            return maxValue;

        long temp;
        while ((temp = maxValue % minValue) != 0) {
            maxValue = minValue;
            minValue = temp;
        }

        return (long) (val3 / minValue);
    }

    static String nextPermutation(String s) {
        ArrayList<Character> list = new ArrayList<>();
        for (int i = 0; i < s.length(); i++)
            list.add(s.charAt(i));

        int pivotPos = -1;
        char pivot = 0;
        for (int i = list.size() - 2; i >= 0; i--) {
            if (list.get(i) < list.get(i + 1)) {
                pivotPos = i;
                pivot = list.get(i);
                break;
            }
        }

        if (pivotPos == -1 && pivot == 0)
            return "Final";

        int L = pivotPos + 1, R = list.size() - 1;
        int minPos = -1;
        char min = Character.MAX_VALUE;
        for (int i = R; i >= L; i--) {
            if (pivot < list.get(i)) {
                if (list.get(i) < min) {
                    min = list.get(i);
                    minPos = i;
                }
            }
        }

        Collections.swap(list, pivotPos, minPos);
        Collections.sort(list.subList(L, R + 1));

        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < list.size(); i++)
            sb.append(list.get(i));

        return sb.toString();

    }

    public List<String> permutation(List<String> list, String target, String ans) {
        if (target.length() <= 1) {
            list.add(ans + target);
        } else {
            for (int i = 0; i < target.length(); i++) {
                permutation(list, target.substring(0, i) + target.substring(i + 1), ans + target.charAt(i));
            }
        }
        return list;
    }

    public static int lowerbound(int[] a, int key) {
        if (a[a.length - 1] < key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] < key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int upperbound(int[] a, int key) {
        if (a[a.length - 1] <= key)
            return a.length;
        int lb = 0, ub = a.length - 1, mid;
        do {
            mid = (ub + lb) / 2;
            if (a[mid] <= key)
                lb = mid + 1;
            else
                ub = mid;
        } while (lb < ub);
        return ub;
    }

    public static int count(int[] a, int key) {
        return upperbound(a, key) - lowerbound(a, key);
    }

    public static void main(String[] args) {
        FastScanner fs = new FastScanner();
        int[][] a = new int[3][3];
        int sum = 0;
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                a[i][j] = fs.nextInt();
                sum += a[i][j];
            }
        }
        System.out.println(sum % 3 == 0 && (sum / 3) == a[0][0] + a[1][1] + a[2][2] ? "Yes" : "No");
    }

}
