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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	}

} import java.util.Scanner; Scanner java.util public class Main {

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

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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	}

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

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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	} main {
		Scanner sc = new Scanner(System.in);
		int c[][] = new int[3][3];

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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int c[][] = new int[3][3]; c new int[3][3] 3 3 int sum = 0; sum 0 for (int i = 0; i < 3; i++) {
			for (int j = 0; j < 3; j++) {
				c[i][j] = sc.nextInt();
				sum += c[i][j];
			}
		} int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i {
			for (int j = 0; j < 3; j++) {
				c[i][j] = sc.nextInt();
				sum += c[i][j];
			}
		} {
			for (int j = 0; j < 3; j++) {
				c[i][j] = sc.nextInt();
				sum += c[i][j];
			}
		} for (int j = 0; j < 3; j++) {
				c[i][j] = sc.nextInt();
				sum += c[i][j];
			} int j = 0; int j = 0; j 0 j < 3 j 3 j++ j++ j {
				c[i][j] = sc.nextInt();
				sum += c[i][j];
			} {
				c[i][j] = sc.nextInt();
				sum += c[i][j];
			} c[i][j] = sc.nextInt() c[i][j] c[i] c i j sc.nextInt() sc.nextInt sc sum += c[i][j] sum c[i][j] c[i] c i j if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		} sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2] sum % 3 != 0 sum % 3 sum 3 0 sum / 3 != c[0][0] + c[1][1] + c[2][2] sum / 3 sum 3 c[0][0] + c[1][1] + c[2][2] c[0][0] + c[1][1] + c[2][2] c[0][0] c[0] c 0 0 c[1][1] c[1] c 1 1 c[2][2] c[2] c 2 2 {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" sc.close() sc.close sc String[] args args public class Main {

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

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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	}

} public class Main {

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

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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	}

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

		if (sum % 3 != 0 || sum / 3 != c[0][0] + c[1][1] + c[2][2]) {
			System.out.println("No");
		} else {
			System.out.println("Yes");
		}

		sc.close();

	}

}