import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int[][] c = new int[3][3];
		int ans = 0;

		for(int i=0; i<3; i++) {
			for(int j=0; j<3; j++) {
				c[i][j] = sc.nextInt();
			}
		}

		if(c[0][2]-c[0][1] == c[1][2]-c[1][1]
				&& c[0][2]-c[0][1] == c[2][2]-c[2][1]) {
			ans += 1;
		}if(c[0][0]-c[0][1] == c[1][0]-c[1][1]
				&& c[0][0]-c[0][1] == c[2][0]-c[2][1]) {
			ans += 1;
		}if(c[2][0]-c[1][0] == c[2][1]-c[1][1]
				&& c[2][0]-c[1][0] == c[2][2]-c[1][2]) {
			ans += 1;
		}if(c[0][0]-c[1][0] == c[0][1]-c[1][1]
				&& c[0][0]-c[1][0] == c[0][2]-c[1][2]) {
			ans += 1;
		}

		if(ans == 4) {
			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