import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} Main public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	} main {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	} Scanner stdIn=new Scanner(System.in); stdIn new Scanner(System.in) int c[][]=new int[3][3]; c new int[3][3] 3 3 int z=0 z 0 y=0 y 0 fin=0 fin 0 a1=0 a1 0 a2=0; a2 0 while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		} z<3 z 3 {
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		} while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			} y<3 y 3 {
				c[z][y]=stdIn.nextInt();
				y++;
			} c[z][y]=stdIn.nextInt() c[z][y] c[z] c z y stdIn.nextInt() stdIn.nextInt stdIn y++ y y=0 y 0 z++ z z=1 z 1 a1=c[0][0]-c[0][1] a1 c[0][0]-c[0][1] c[0][0] c[0] c 0 0 c[0][1] c[0] c 0 1 a2=c[0][1]-c[0][2] a2 c[0][1]-c[0][2] c[0][1] c[0] c 0 1 c[0][2] c[0] c 0 2 while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		} z<3 z 3 {
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		} if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			} c[z][0]-c[z][1]!=a1 c[z][0]-c[z][1] c[z][0] c[z] c z 0 c[z][1] c[z] c z 1 a1 {
				fin=1;
				break;
			} fin=1 fin 1 break; if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			} c[z][1]-c[z][2]!=a2 c[z][1]-c[z][2] c[z][1] c[z] c z 1 c[z][2] c[z] c z 2 a2 {
				fin=1;
				break;
			} fin=1 fin 1 break; z++ z if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes"); fin==1 fin 1 System.out.println("No") System.out.println System.out System System.out "No" System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} public class Main {
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

} Main
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int c[][]=new int[3][3];
		int z=0,y=0,fin=0,a1=0,a2=0;
		while(z<3){
			while(y<3){
				c[z][y]=stdIn.nextInt();
				y++;
			}y=0;
			z++;
		}z=1;
		a1=c[0][0]-c[0][1];
		a2=c[0][1]-c[0][2];
		while(z<3){
			if(c[z][0]-c[z][1]!=a1){
				fin=1;
				break;
			}
			if(c[z][1]-c[z][2]!=a2){
				fin=1;
				break;
			}
			z++;
		}
		if(fin==1)
			System.out.println("No");
		else
			System.out.println("Yes");
	}

}