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();
            }
        }
        int sum1 = c[0][0] + c[1][1] + c[2][2];
        int sum2 = c[2][0] + c[0][1] + c[1][2];
        int sum3 = c[1][0] + c[2][1] + c[0][2];
        if(sum1 == sum2 && sum2 == sum3){
            System.out.println("Yes");
        }else{
            System.out.println("No");
        }
    }
}

/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