import java.util.*;

import static java.lang.System.*;

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[2][1] - c[1][1] == c[2][2] - c[1][2] &&
                c[2][1] - c[1][1] == c[2][3] - c[1][3] &&
                c[3][1] - c[1][1] == c[3][2] - c[1][2] &&
                c[3][1] - c[1][1] == c[3][3] - c[1][3]) {
            out.println("Yes");
        } else {
            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