import java.util.Scanner;
import java.util.Arrays;

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();
            }
        }
        boolean ans = true;
        for (int i = 0; i < 2; i++) {
            if (c[0][i] - c[0][i + 1] != c[1][i] - c[1][i + 1]) {
                ans = false;
                break;
            }
            if (c[1][i] - c[1][i + 1] != c[2][i] - c[2][i + 1]) {
                ans = false;
                break;
            }
        }
        if (ans == true) {
            for (int i = 0; i < 2; i++) {
                if (c[i][0] - c[i + 1][0] != c[i][1] - c[i + 1][1]) {
                    ans = false;
                    break;
                }
                if (c[i][1] - c[i + 1][1] != c[i][2] - c[i + 1][2]) {
                    ans = false;
                    break;
                }
            }
        }
        if (ans == true) {
            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