import java.util.*;

public class Main {

    public static String printAnswer(int[][] c) {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    }

} import java.util.*; util.* java public class Main {

    public static String printAnswer(int[][] c) {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    }

} Main public static String printAnswer(int[][] c) {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    } printAnswer {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    } int col1 = 0; col1 0 int col2 = 0; col2 0 int col3 = 0; col3 0 int row1 = 0; row1 0 int row2 = 0; row2 0 int row3 = 0; row3 0 for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        } int i = 1; int i = 1; i 1 i < 3 i 3 i++ i++ i {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        } {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        } col1 = c[0][0] - c[i][0] col1 c[0][0] - c[i][0] c[0][0] c[0] c 0 0 c[i][0] c[i] c i 0 col2 = c[0][1] - c[i][1] col2 c[0][1] - c[i][1] c[0][1] c[0] c 0 1 c[i][1] c[i] c i 1 col3 = c[0][2] - c[i][2] col3 c[0][2] - c[i][2] c[0][2] c[0] c 0 2 c[i][2] c[i] c i 2 if (col1 != col2 || col2 != col3) {
                return "No";
            } col1 != col2 || col2 != col3 col1 != col2 col1 col2 col2 != col3 col2 col3 {
                return "No";
            } return "No"; "No" row1 = c[0][0] - c[0][i] row1 c[0][0] - c[0][i] c[0][0] c[0] c 0 0 c[0][i] c[0] c 0 i row2 = c[1][0] - c[1][i] row2 c[1][0] - c[1][i] c[1][0] c[1] c 1 0 c[1][i] c[1] c 1 i row3 = c[2][0] - c[2][i] row3 c[2][0] - c[2][i] c[2][0] c[2] c 2 0 c[2][i] c[2] c 2 i if (row1 != row2 || row2 != row3) {
                return "No";
            } row1 != row2 || row2 != row3 row1 != row2 row1 row2 row2 != row3 row2 row3 {
                return "No";
            } return "No"; "No" return "Yes"; "Yes" int[][] c c public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    } main {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int[][] c = new int[3][3]; c new int[3][3] 3 3 for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        } int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        } {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        } for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            } int j = 0; int j = 0; j 0 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 System.out.println(printAnswer(c)) System.out.println System.out System System.out printAnswer(c) printAnswer c String[] args args public class Main {

    public static String printAnswer(int[][] c) {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    }

} public class Main {

    public static String printAnswer(int[][] c) {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    }

} Main
import java.util.*;

public class Main {

    public static String printAnswer(int[][] c) {
        int col1 = 0;
        int col2 = 0;
        int col3 = 0;
        int row1 = 0;
        int row2 = 0;
        int row3 = 0;
        for (int i = 1; i < 3; i++) {
            col1 = c[0][0] - c[i][0];
            col2 = c[0][1] - c[i][1];
            col3 = c[0][2] - c[i][2];
            if (col1 != col2 || col2 != col3) {
                return "No";
            }
            row1 = c[0][0] - c[0][i];
            row2 = c[1][0] - c[1][i];
            row3 = c[2][0] - c[2][i];
            if (row1 != row2 || row2 != row3) {
                return "No";
            }
        }
        return "Yes";
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[][] c = new int[3][3];
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                c[i][j] = sc.nextInt();
            }
        }
        System.out.println(printAnswer(c));
    }

}
