import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author anand.oza
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    }

    static class CTakahashisInformation {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.StringTokenizer; StringTokenizer java.util import java.io.IOException; IOException java.io import java.io.BufferedReader; BufferedReader java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.InputStream; InputStream java.io public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    }

    static class CTakahashisInformation {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) CTakahashisInformation solver = new CTakahashisInformation(); solver new CTakahashisInformation() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class CTakahashisInformation {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        }

    } CTakahashisInformation public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        } solve {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        } 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] = in.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] = in.nextInt();
                }
            } {
                for (int j = 0; j < n; j++) {
                    c[i][j] = in.nextInt();
                }
            } for (int j = 0; j < n; j++) {
                    c[i][j] = in.nextInt();
                } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                    c[i][j] = in.nextInt();
                } {
                    c[i][j] = in.nextInt();
                } c[i][j] = in.nextInt() c[i][j] c[i] c i j in.nextInt() in.nextInt in int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]}; a {c[0][0],
                       c[1][0],
                       c[2][0]} c[0][0] c[0] c 0 0 c[1][0] c[1] c 1 0 c[2][0] c[2] c 2 0 int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]}; b {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]} 0 c[0][1] - c[0][0] c[0][1] c[0] c 0 1 c[0][0] c[0] c 0 0 c[0][2] - c[0][0] c[0][2] c[0] c 0 2 c[0][0] c[0] c 0 0 boolean answer = true; answer true for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            } {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            } for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
                    answer &= c[i][j] == a[i] + b[j];
                } {
                    answer &= c[i][j] == a[i] + b[j];
                } answer &= c[i][j] == a[i] + b[j] answer c[i][j] == a[i] + b[j] c[i][j] c[i] c i j a[i] + b[j] a[i] a i b[j] b j out.println(answer ? "Yes" : "No") out.println out answer ? "Yes" : "No" answer "Yes" "No" int testNumber testNumber InputReader in in PrintWriter out out static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    } InputReader public BufferedReader reader; reader public StringTokenizer tokenizer; tokenizer public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } InputReader {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        } reader = new BufferedReader(new InputStreamReader(stream), 32768) reader new BufferedReader(new InputStreamReader(stream), 32768) tokenizer = null tokenizer null InputStream stream stream public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } next {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            } try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                } IOException e {
                    throw new RuntimeException(e);
                } throw new RuntimeException(e); new RuntimeException(e) {
                    tokenizer = new StringTokenizer(reader.readLine());
                } tokenizer = new StringTokenizer(reader.readLine()) tokenizer new StringTokenizer(reader.readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public int nextInt() {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    }

    static class CTakahashisInformation {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    }

    static class CTakahashisInformation {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author anand.oza
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        CTakahashisInformation solver = new CTakahashisInformation();
        solver.solve(1, in, out);
        out.close();
    }

    static class CTakahashisInformation {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            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] = in.nextInt();
                }
            }

            int[] a = {c[0][0],
                       c[1][0],
                       c[2][0]};
            int[] b = {0,
                       c[0][1] - c[0][0],
                       c[0][2] - c[0][0]};

            boolean answer = true;
            for (int i = 0; i < n; i++) {
                for (int j = 0; j < n; j++) {
                    answer &= c[i][j] == a[i] + b[j];
                }
            }

            out.println(answer ? "Yes" : "No");
        }

    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

    }
}

