import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan = 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]=scan.nextInt();
			}
		}
		scan.close();
		int check=0;
		for(int i=0;i<2;i++) {
			for(int j=0;j<2;j++) {
				if(c[j][i]-c[j][i+1] !=  c[j+1][i]-c[j+1][i+1]) {
					check=1;break;
				}
			}
			if(check==1)break;
		}

		for(int i=0;i<2;i++) {
			for(int j=0;j<2;j++) {
				if(c[i][j]-c[i+1][j] !=  c[i][j+1]-c[i+1][j+1]) {
					check=1;break;
				}
			}
			if(check==1)break;
		}

		System.out.println((check==0)?"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