import java.util.*;
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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "No");
	}

} import java.util.*; util.* 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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "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] c[i] c i j sc.nextInt() sc.nextInt sc boolean ok = true; ok true for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		} int i = 1; int i = 1; i 1 i <= 2 i 2 i++ i++ i {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		} {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		} if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false; c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1] c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] c[0][i] - c[0][i-1] c[0][i] c[0] c 0 i c[0][i-1] c[0] c 0 i-1 i 1 c[1][i] - c[1][i-1] c[1][i] c[1] c 1 i c[1][i-1] c[1] c 1 i-1 i 1 c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1] c[0][i] - c[0][i-1] c[0][i] c[0] c 0 i c[0][i-1] c[0] c 0 i-1 i 1 c[2][i] - c[2][i-1] c[2][i] c[2] c 2 i c[2][i-1] c[2] c 2 i-1 i 1 ok = false ok false for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		} int i = 1; int i = 1; i 1 i <= 2 i 2 i++ i++ i {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		} {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		} if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false; c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2] c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] c[i][0] - c[i-1][0] c[i][0] c[i] c i 0 c[i-1][0] c[i-1] c i-1 i 1 0 c[i][1] - c[i-1][1] c[i][1] c[i] c i 1 c[i-1][1] c[i-1] c i-1 i 1 1 c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2] c[i][0] - c[i-1][0] c[i][0] c[i] c i 0 c[i-1][0] c[i-1] c i-1 i 1 0 c[i][2] - c[i-1][2] c[i][2] c[i] c i 2 c[i-1][2] c[i-1] c i-1 i 1 2 ok = false ok false System.out.println(ok ? "Yes" : "No") System.out.println System.out System System.out ok ? "Yes" : "No" ok "Yes" "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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "No");
	}

} Main
import java.util.*;
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();
		}
		boolean ok = true;
		for(int i = 1; i <= 2; i++) {
			if(c[0][i] - c[0][i-1] != c[1][i] - c[1][i-1] || c[0][i] - c[0][i-1] != c[2][i] - c[2][i-1])
				ok = false;
		}
		for(int i = 1; i <= 2; i++) {
			if(c[i][0] - c[i-1][0] != c[i][1] - c[i-1][1] || c[i][0] - c[i-1][0] != c[i][2] - c[i-1][2])
				ok = false;
		}
		System.out.println(ok ? "Yes" : "No");
	}

}