import java.util.*;
import java.lang.*;


public class Main {
    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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} import java.util.*; util.* java import java.lang.*; lang.* java public class Main {
    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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} Main 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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    } 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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    } 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 int a = c[1][0] - c[0][0]; a c[1][0] - c[0][0] c[1][0] c[1] c 1 0 c[0][0] c[0] c 0 0 int b = c[2][0] - c[1][0]; b c[2][0] - c[1][0] c[2][0] c[2] c 2 0 c[1][0] c[1] c 1 0 int x = c[0][1] - c[0][0]; x c[0][1] - c[0][0] c[0][1] c[0] c 0 1 c[0][0] c[0] c 0 0 int y = c[0][2] - c[0][1]; y c[0][2] - c[0][1] c[0][2] c[0] c 0 2 c[0][1] c[0] c 0 1 boolean correct = true; correct true if (c[1][1] != c[0][0] + x + a) correct = false; c[1][1] != c[0][0] + x + a c[1][1] c[1] c 1 1 c[0][0] + x + a c[0][0] + x + a c[0][0] c[0] c 0 0 x a correct = false correct false if (c[1][2] != c[0][0] + x + y + a) correct = false; c[1][2] != c[0][0] + x + y + a c[1][2] c[1] c 1 2 c[0][0] + x + y + a y c[0][0] + x + y + a c[0][0] c[0] c 0 0 x y a correct = false correct false if (c[2][1] != c[0][0] + x + a + b) correct = false; c[2][1] != c[0][0] + x + a + b c[2][1] c[2] c 2 1 c[0][0] + x + a + b a c[0][0] + x + a + b c[0][0] c[0] c 0 0 x a b correct = false correct false if (c[2][2] != c[0][0] + x + y + a + b) correct = false; c[2][2] != c[0][0] + x + y + a + b c[2][2] c[2] c 2 2 c[0][0] + x + y + a + b a y c[0][0] + x + y + a + b c[0][0] c[0] c 0 0 x y a b correct = false correct false if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        } correct {
            System.out.println("Yes");
        } System.out.println("Yes") System.out.println System.out System System.out "Yes" {
            System.out.println("No");
        } System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main {
    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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} public class Main {
    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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
} Main
import java.util.*;
import java.lang.*;


public class Main {
    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();
            }
        }
        int a = c[1][0] - c[0][0];
        int b = c[2][0] - c[1][0];
        int x = c[0][1] - c[0][0];
        int y = c[0][2] - c[0][1];
        boolean correct = true;
        if (c[1][1] != c[0][0] + x + a) correct = false;
        if (c[1][2] != c[0][0] + x + y + a) correct = false;
        if (c[2][1] != c[0][0] + x + a + b) correct = false;
        if (c[2][2] != c[0][0] + x + y + a + b) correct = false;
        if (correct) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
    }
}