import java.util.Arrays;
import java.util.Scanner;

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

		sc.close();
	}
} import java.util.Arrays; Arrays java.util import java.util.Scanner; Scanner java.util 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[1][1]-c[2][1]==c[1][2]-c[2][2]
		 &&c[1][1]-c[2][1]==c[1][3]-c[2][3]
		 &&c[3][1]-c[2][1]==c[3][2]-c[2][2]
		 &&c[3][1]-c[2][1]==c[3][3]-c[2][3]
		 &&c[1][2]-c[1][1]==c[2][2]-c[2][1]
		 &&c[1][2]-c[1][1]==c[3][2]-c[3][1]
		 &&c[1][3]-c[1][2]==c[2][3]-c[2][2]
		 &&c[1][3]-c[1][2]==c[3][3]-c[3][2]){
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}

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

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

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

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

		sc.close();
	}
} Main
import java.util.Arrays;
import java.util.Scanner;

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

		sc.close();
	}
}
