import java.util.*;
import java.util.Arrays;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	}
} import java.util.*; util.* java import java.util.Arrays; Arrays java.util public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	}
} Main public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	} main {
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) int[] A=new int[3]; A new int[3] 3 int[] diffe=new int[2]; diffe new int[2] 2 int[] diffe_tmp=new int[2]; diffe_tmp new int[2] 2 int flag=0; flag 0 String ans="null"; ans "null" for(int i=0;i<3;i++) A[i]=sc.nextInt(); int i=0; int i=0; i 0 i<3 i 3 i++ i++ i A[i]=sc.nextInt(); A[i]=sc.nextInt() A[i] A i sc.nextInt() sc.nextInt sc diffe[0]=A[0]-A[1] diffe[0] diffe 0 A[0]-A[1] A[0] A 0 A[1] A 1 diffe[1]=A[1]-A[2] diffe[1] diffe 1 A[1]-A[2] A[1] A 1 A[2] A 2 for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		} int i=0; int i=0; i 0 i<=1 i 1 i++ i++ i {
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		} {
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		} for(int j=0;j<3;j++) A[j]=sc.nextInt(); int j=0; int j=0; j 0 j<3 j 3 j++ j++ j A[j]=sc.nextInt(); A[j]=sc.nextInt() A[j] A j sc.nextInt() sc.nextInt sc diffe_tmp[0]=A[0]-A[1] diffe_tmp[0] diffe_tmp 0 A[0]-A[1] A[0] A 0 A[1] A 1 diffe_tmp[1]=A[1]-A[2] diffe_tmp[1] diffe_tmp 1 A[1]-A[2] A[1] A 1 A[2] A 2 if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1; diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1] diffe[0]!=diffe_tmp[0] diffe[0] diffe 0 diffe_tmp[0] diffe_tmp 0 diffe_tmp[1]!=diffe[1] diffe_tmp[1] diffe_tmp 1 diffe[1] diffe 1 flag=1 flag 1 if(flag==0) ans="Yes";
		else ans="No"; flag==0 flag 0 ans="Yes" ans "Yes" ans="No" ans "No" System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	}
} Main
import java.util.*;
import java.util.Arrays;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		int[] A=new int[3];
		int[] diffe=new int[2];
		int[] diffe_tmp=new int[2];
		int flag=0;
		String ans="null";

		for(int i=0;i<3;i++) A[i]=sc.nextInt();

		diffe[0]=A[0]-A[1];
		diffe[1]=A[1]-A[2];

		for(int i=0;i<=1;i++){
			for(int j=0;j<3;j++) A[j]=sc.nextInt();

			diffe_tmp[0]=A[0]-A[1];
			diffe_tmp[1]=A[1]-A[2];
			if(diffe[0]!=diffe_tmp[0] || diffe_tmp[1]!=diffe[1]) flag=1;
		}
		
		if(flag==0) ans="Yes";
		else ans="No";

		System.out.println(ans);
	}
}