import 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();
        }
      }
      String ans = "Yes";
      for(int i = 0; i < 2; i++){
        if(!(c[0][i]-c[0][i+1]==c[1][i]-c[1][i+1] && c[0][i]-c[0][i+1]==c[2][i]-c[2][i+1])){
           ans = "No";
        }
      }
      System.out.println(ans);
    }
}
/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