import java.util.*;

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();
			}
		}

		for(int i=0; i<=100; i++){
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		}
		System.out.println("No");

	}
}

 import java.util.*; util.* java 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();
			}
		}

		for(int i=0; i<=100; i++){
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		}
		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();
			}
		}

		for(int i=0; i<=100; i++){
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		}
		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();
			}
		}

		for(int i=0; i<=100; i++){
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		}
		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 for(int i=0; i<=100; i++){
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		} int i=0; int i=0; i 0 i<=100 i 100 i++ i++ i {
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		} {
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		} int a = i; a i int b1 = c[0][0] - i; b1 c[0][0] - i c[0][0] c[0] c 0 0 i int b2 = c[0][1] - i; b2 c[0][1] - i c[0][1] c[0] c 0 1 i int b3 = c[0][2] - i; b3 c[0][2] - i c[0][2] c[0] c 0 2 i if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			} c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3 c[1][0] - b1 == c[1][1] - b2 c[1][0] - b1 c[1][0] c[1] c 1 0 b1 c[1][1] - b2 c[1][1] c[1] c 1 1 b2 c[1][1] - b2 == c[1][2] - b3 c[1][1] - b2 c[1][1] c[1] c 1 1 b2 c[1][2] - b3 c[1][2] c[1] c 1 2 b3 {
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			} if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				} c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3 c[2][0] - b1 == c[2][1] - b2 c[2][0] - b1 c[2][0] c[2] c 2 0 b1 c[2][1] - b2 c[2][1] c[2] c 2 1 b2 c[2][1] - b2 == c[2][2] - b3 c[2][1] - b2 c[2][1] c[2] c 2 1 b2 c[2][2] - b3 c[2][2] c[2] c 2 2 b3 {
					System.out.println("Yes");
					return;
				} System.out.println("Yes") System.out.println System.out System System.out "Yes" return; System.out.println("No") System.out.println System.out System System.out "No" String[] args args
import java.util.*;

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();
			}
		}

		for(int i=0; i<=100; i++){
			int a = i;
			int b1 = c[0][0] - i;
			int b2 = c[0][1] - i;
			int b3 = c[0][2] - i;

			if(c[1][0] - b1 == c[1][1] - b2 && c[1][1] - b2 == c[1][2] - b3){
				if(c[2][0] - b1 == c[2][1] - b2 && c[2][1] - b2 == c[2][2] - b3){
					System.out.println("Yes");
					return;
				}
			}
		}
		System.out.println("No");

	}
}


