import java.util.*; 

class Main{
public static void main(String[] args){
	Scanner sc=new Scanner(System.in);

  		int[][] ci=new int[3][3];
		for(int c=0;c<3;c++){
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	}
    int count=0;
  	for(int b=0;b<2;b++){
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    }
    for(int b=0;b<2;b++){
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    }
 	if(count==0){
    		System.out.println("Yes");
    	}else{
     		System.out.println("No");
   	 }


    }
} import java.util.*; util.* java class Main{
public static void main(String[] args){
	Scanner sc=new Scanner(System.in);

  		int[][] ci=new int[3][3];
		for(int c=0;c<3;c++){
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	}
    int count=0;
  	for(int b=0;b<2;b++){
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    }
    for(int b=0;b<2;b++){
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    }
 	if(count==0){
    		System.out.println("Yes");
    	}else{
     		System.out.println("No");
   	 }


    }
} Main public static void main(String[] args){
	Scanner sc=new Scanner(System.in);

  		int[][] ci=new int[3][3];
		for(int c=0;c<3;c++){
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	}
    int count=0;
  	for(int b=0;b<2;b++){
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    }
    for(int b=0;b<2;b++){
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    }
 	if(count==0){
    		System.out.println("Yes");
    	}else{
     		System.out.println("No");
   	 }


    } main {
	Scanner sc=new Scanner(System.in);

  		int[][] ci=new int[3][3];
		for(int c=0;c<3;c++){
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	}
    int count=0;
  	for(int b=0;b<2;b++){
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    }
    for(int b=0;b<2;b++){
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    }
 	if(count==0){
    		System.out.println("Yes");
    	}else{
     		System.out.println("No");
   	 }


    } Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int[][] ci=new int[3][3]; ci new int[3][3] 3 3 for(int c=0;c<3;c++){
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	} int c=0; int c=0; c 0 c<3 c 3 c++ c++ c {
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	} {
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	} ci[c][0]=sc.nextInt() ci[c][0] ci[c] ci c 0 sc.nextInt() sc.nextInt sc ci[c][1]=sc.nextInt() ci[c][1] ci[c] ci c 1 sc.nextInt() sc.nextInt sc ci[c][2]=sc.nextInt() ci[c][2] ci[c] ci c 2 sc.nextInt() sc.nextInt sc int count=0; count 0 for(int b=0;b<2;b++){
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    } int b=0; int b=0; b 0 b<2 b 2 b++ b++ b {
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    } {
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    } if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     } (ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2]) (ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1]) (ci[b+1][0]-ci[b][0]) ci[b+1][0] ci[b+1] ci b+1 b 1 0 ci[b][0] ci[b] ci b 0 (ci[b+1][1]-ci[b][1]) ci[b+1][1] ci[b+1] ci b+1 b 1 1 ci[b][1] ci[b] ci b 1 (ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2]) (ci[b+1][1]-ci[b][1]) ci[b+1][1] ci[b+1] ci b+1 b 1 1 ci[b][1] ci[b] ci b 1 (ci[b+1][2]-ci[b][2]) ci[b+1][2] ci[b+1] ci b+1 b 1 2 ci[b][2] ci[b] ci b 2 {
     	count=1;
     } count=1 count 1 for(int b=0;b<2;b++){
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    } int b=0; int b=0; b 0 b<2 b 2 b++ b++ b {
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    } {
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    } if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     } (ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b]) (ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b]) (ci[0][b+1]-ci[0][b]) ci[0][b+1] ci[0] ci 0 b+1 b 1 ci[0][b] ci[0] ci 0 b (ci[1][b+1]-ci[1][b]) ci[1][b+1] ci[1] ci 1 b+1 b 1 ci[1][b] ci[1] ci 1 b (ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b]) (ci[1][b+1]-ci[1][b]) ci[1][b+1] ci[1] ci 1 b+1 b 1 ci[1][b] ci[1] ci 1 b (ci[2][b+1]-ci[2][b]) ci[2][b+1] ci[2] ci 2 b+1 b 1 ci[2][b] ci[2] ci 2 b {
     	count=1;
     } count=1 count 1 if(count==0){
    		System.out.println("Yes");
    	}else{
     		System.out.println("No");
   	 } count==0 count 0 {
    		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
import java.util.*; 

class Main{
public static void main(String[] args){
	Scanner sc=new Scanner(System.in);

  		int[][] ci=new int[3][3];
		for(int c=0;c<3;c++){
    		ci[c][0]=sc.nextInt();
          	ci[c][1]=sc.nextInt();
         	ci[c][2]=sc.nextInt();
    	}
    int count=0;
  	for(int b=0;b<2;b++){
     if((ci[b+1][0]-ci[b][0])!=(ci[b+1][1]-ci[b][1])||(ci[b+1][1]-ci[b][1])!=(ci[b+1][2]-ci[b][2])){
     	count=1;
     }
    }
    for(int b=0;b<2;b++){
     if((ci[0][b+1]-ci[0][b])!=(ci[1][b+1]-ci[1][b])||(ci[1][b+1]-ci[1][b])!=(ci[2][b+1]-ci[2][b])){
     	count=1;
     }
    }
 	if(count==0){
    		System.out.println("Yes");
    	}else{
     		System.out.println("No");
   	 }


    }
}
