import java.util.Scanner;

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 s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
	}

} 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[3][3];
		for(int i=0;i<3;i++){
			for(int j=0;j<3;j++){
				c[i][j]=sc.nextInt();
			}
		}
		int s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			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 s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			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 s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			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 s1=c[0][1]+c[0][2]+c[1][2]; s1 c[0][1]+c[0][2]+c[1][2] c[0][1]+c[0][2]+c[1][2] c[0][1] c[0] c 0 1 c[0][2] c[0] c 0 2 c[1][2] c[1] c 1 2 int s2=c[1][0]+c[2][0]+c[2][1]; s2 c[1][0]+c[2][0]+c[2][1] c[1][0]+c[2][0]+c[2][1] c[1][0] c[1] c 1 0 c[2][0] c[2] c 2 0 c[2][1] c[2] c 2 1 int s=c[0][0]+c[1][1]+c[2][2]; s c[0][0]+c[1][1]+c[2][2] c[0][0]+c[1][1]+c[2][2] c[0][0] c[0] c 0 0 c[1][1] c[1] c 1 1 c[2][2] c[2] c 2 2 if(s1+s2==2*s){
			System.out.println("Yes");
		}else{
			System.out.println("No");
		} s1+s2==2*s s1+s2 s1 s2 2*s 2 s {
			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 s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			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 s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
	}

} Main
import java.util.Scanner;

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 s1=c[0][1]+c[0][2]+c[1][2];
		int s2=c[1][0]+c[2][0]+c[2][1];
		int s=c[0][0]+c[1][1]+c[2][2];
		if(s1+s2==2*s){
			System.out.println("Yes");
		}else{
			System.out.println("No");
		}
	}

}