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++) {
			c[0][i] = sc.nextInt();
			c[1][i] = sc.nextInt();
			c[2][i] = sc.nextInt();
		}

		for (int i = 1 ; i < 3 ; i++) {
			for (int j = 1 ; j < 3 ; j++) {
				if (c[i-1][j-1] - c[i][j-1] != c[i-1][j] - c[i][j]) {
					System.out.println("No");
					System.exit(0);
				}
			}
		}
		System.out.println("Yes");
	}
}

/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