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();
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz