import java.util.Scanner;
public class Main{
    static int[][] mat = new int[3][3];
    public static void main(String[] args){
    	Scanner sc = new Scanner(System.in);
        int i, j;
        for(i = 0; i < 3; i++){
            for(j = 0; j < 3; j++){
                mat[i][j] = sc.nextInt();
            }
        }
        
        System.out.println(
        (mat[0][0] - mat[0][1] == mat[1][0] - mat[1][1] && mat[1][0] - mat[1][1] == mat[2][0] - mat[2][1] &&
         mat[0][1] - mat[0][2] == mat[1][1] - mat[1][2] && mat[1][1] - mat[1][2] == mat[2][1] - mat[2][2] &&
         mat[0][0] - mat[1][0] == mat[0][1] - mat[1][1] && mat[0][1] - mat[1][1] == mat[0][2] - mat[1][2] &&
         mat[1][0] - mat[2][0] == mat[1][1] - mat[2][1] && mat[1][1] - mat[2][1] == mat[1][2] - mat[2][2])
        ? "Yes" : "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