import java.util.*;
public class Main {
	public static void main(String[] args){
       Scanner sc = new Scanner(System.in);
      //取得
      int[] c = new int[9];
      for(int i=0; i<9; ++i){
        c[i] = sc.nextInt();
      }
      int d1 = c[1]-c[0];
      int d2 = c[2]-c[1];
      String ans = "Yes";
      if(c[4]!=c[3]+d1){
        ans="No";
      } if(c[7]!=c[6]+d1){
        ans="No";
      } if(c[5]!=c[4]+d2){
        ans="No";
      } if(c[8]!=c[7]+d2){
        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