import java.util.*;

import static java.lang.System.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    }
} import java.util.*; util.* java import static java.lang.System.*; import static java.lang.System.*; import static java.lang.System.*; public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    } main {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int[][] c = new int[4][4]; c new int[4][4] 4 4 for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        } int i = 1; int i = 1; i 1 i <= 3 i 3 i++ i++ i {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        } {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        } for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            } int j = 1; int j = 1; j 1 j <= 3 j 3 j++ j++ j {
                c[i][j] = sc.nextInt();
            } {
                c[i][j] = sc.nextInt();
            } c[i][j] = sc.nextInt() c[i][j] c[i] c i j sc.nextInt() sc.nextInt sc if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        } c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3] c[3][1] - c[1][1] == c[3][2] - c[1][2] c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3] c[2][1] - c[1][1] == c[2][2] - c[1][2] c[2][1] - c[1][1] c[2][1] c[2] c 2 1 c[1][1] c[1] c 1 1 c[2][2] - c[1][2] c[2][2] c[2] c 2 2 c[1][2] c[1] c 1 2 c[2][1] - c[1][1] == c[2][3] - c[1][3] c[2][1] - c[1][1] c[2][1] c[2] c 2 1 c[1][1] c[1] c 1 1 c[2][3] - c[1][3] c[2][3] c[2] c 2 3 c[1][3] c[1] c 1 3 c[3][1] - c[1][1] == c[3][2] - c[1][2] c[3][1] - c[1][1] c[3][1] c[3] c 3 1 c[1][1] c[1] c 1 1 c[3][2] - c[1][2] c[3][2] c[3] c 3 2 c[1][2] c[1] c 1 2 c[3][1] - c[1][1] == c[3][3] - c[1][3] c[3][1] - c[1][1] c[3][1] c[3] c 3 1 c[1][1] c[1] c 1 1 c[3][3] - c[1][3] c[3][3] c[3] c 3 3 c[1][3] c[1] c 1 3 {
            out.println("Yes");
        } out.println("Yes") out.println out "Yes" {
            out.println("No");
        } out.println("No") out.println out "No" String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    }
} Main
import java.util.*;

import static java.lang.System.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int[][] c = new int[4][4];

        for (int i = 1; i <= 3; i++) {
            for (int j = 1; j <= 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }

        if (c[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            out.println("No");
        }
    }
}