import java.io.IOException;
import java.util.NoSuchElementException;

import java.io.InputStream;

import java.io.PrintWriter;

@SuppressWarnings("unchecked")
public class Main {
    public static void main(String[] args) throws IOException {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    }
}

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());
    }
} import java.io.IOException; IOException java.io import java.util.NoSuchElementException; NoSuchElementException java.util import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io public class Main {
    public static void main(String[] args) throws IOException {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    }
} Main public static void main(String[] args) throws IOException {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    } main {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    } FastScanner fs = new FastScanner(); fs new FastScanner() PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) final int N = 3; N 3 int[][] c = new int[N][N]; c new int[N][N] N N for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt(); int i = 0; int i = 0; i 0 i < N i N i++ i++ i for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt(); for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt(); int j = 0; int j = 0; j 0 j < N j N j++ j++ j c[i][j] = fs.nextInt(); c[i][j] = fs.nextInt() c[i][j] c[i] c i j fs.nextInt() fs.nextInt fs boolean flg = false; flg false if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true; (c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1]) (c[1][0] + c[2][1] == c[1][1] + c[2][0]) (c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1]) (c[0][0] + c[1][1] == c[0][1] + c[1][0]) c[0][0] + c[1][1] c[0][0] c[0] c 0 0 c[1][1] c[1] c 1 1 c[0][1] + c[1][0] c[0][1] c[0] c 0 1 c[1][0] c[1] c 1 0 (c[0][1] + c[1][2] == c[0][2] + c[1][1]) c[0][1] + c[1][2] c[0][1] c[0] c 0 1 c[1][2] c[1] c 1 2 c[0][2] + c[1][1] c[0][2] c[0] c 0 2 c[1][1] c[1] c 1 1 (c[1][0] + c[2][1] == c[1][1] + c[2][0]) c[1][0] + c[2][1] c[1][0] c[1] c 1 0 c[2][1] c[2] c 2 1 c[1][1] + c[2][0] c[1][1] c[1] c 1 1 c[2][0] c[2] c 2 0 (c[1][1] + c[2][2] == c[1][2] + c[2][1]) c[1][1] + c[2][2] c[1][1] c[1] c 1 1 c[2][2] c[2] c 2 2 c[1][2] + c[2][1] c[1][2] c[1] c 1 2 c[2][1] c[2] c 2 1 flg = true flg true out.println(flg ? "Yes" : "No") out.println out flg ? "Yes" : "No" flg "Yes" "No" out.flush() out.flush out String[] args args 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 {
    public static void main(String[] args) throws IOException {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    }
} public class Main {
    public static void main(String[] args) throws IOException {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    }
} Main
import java.io.IOException;
import java.util.NoSuchElementException;

import java.io.InputStream;

import java.io.PrintWriter;

@SuppressWarnings("unchecked")
public class Main {
    public static void main(String[] args) throws IOException {
        FastScanner fs = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);

        final int N = 3;

        int[][] c = new int[N][N];

        for (int i = 0; i < N; i++)
            for (int j = 0; j < N; j++)
                c[i][j] = fs.nextInt();

        // 3つの解法
        // いずれも等価

        // パターン1 たすき掛け検証
        boolean flg = false;

        if ((c[0][0] + c[1][1] == c[0][1] + c[1][0])
            && (c[0][1] + c[1][2] == c[0][2] + c[1][1])
            && (c[1][0] + c[2][1] == c[1][1] + c[2][0])
            && (c[1][1] + c[2][2] == c[1][2] + c[2][1])) flg = true;

        // パターン2 横引き算縦検証
        //boolean flg = false;

        //if ((c[0][0] - c[0][1] == c[1][0] - c[1][1])
        //    && (c[1][0] - c[1][1] == c[2][0] - c[2][1])
        //    && (c[0][1] - c[0][2] == c[1][1] - c[1][2])
        //    && (c[1][1] - c[1][2] == c[2][1] - c[2][2])) flg = true;

        // パターン3 a1をゼロとして検証
        // (a1, a2, a3, b1, b2, b3)
        // = (p1, p2, p3, q1, q2, q3)

        // (p1, p2, p3, q1, q2, q3)
        // = (p1 - x, p2 - x, p3 - x, q1 + x, q2 + x, q3 + x)
        // = (0, p2 - p1, p3 - p1, q1 + p1, q2 + p1, q3 + p1)

        // = (0, c21 - c11, c31 - c11, c11, c12, c13)
        // 0-indexed
        //int[] p = {0, c[1][0] - c[0][0], c[2][0] - c[0][0]};
        //int[] q = {c[0][0], c[0][1], c[0][2]};

        //boolean flg = true;

        // 全項で逐一検証
        //for (int i = 0; i < N; i++)
        //    for (int j = 0; j< N; j++)
        //        if (c[i][j] != p[i] + q[j] ) {
        //            flg = false;
        //            break;
        //        }

        out.println(flg ? "Yes" : "No");

        out.flush();
    }
}

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());
    }
}
