import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.function.Consumer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.ArrayList; ArrayList java.util import java.util.Arrays; Arrays java.util import java.util.HashSet; HashSet java.util import java.util.Set; Set java.util import java.util.function.Consumer; Consumer java.util.function public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	}
} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) int c[][] = new int[3][3]; c new int[3][3] 3 3 for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		} int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		} {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		} String str[] = br.readLine().split(" "); str br.readLine().split(" ") br.readLine().split br.readLine() br.readLine br " " for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			} int j = 0; int j = 0; j 0 j < 3 j 3 j++ j++ j {
				c[i][j] = Integer.parseInt(str[j]);
			} {
				c[i][j] = Integer.parseInt(str[j]);
			} c[i][j] = Integer.parseInt(str[j]) c[i][j] c[i] c i j Integer.parseInt(str[j]) Integer.parseInt Integer str[j] str j for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		} int i = 0; int i = 0; i 0 i < 3 i 3 i++ i++ i {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		} {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		} int s = c[(i + 1) % 3][0] - c[i][0]; s c[(i + 1) % 3][0] - c[i][0] c[(i + 1) % 3][0] c[(i + 1) % 3] c (i + 1) % 3 (i + 1) i 1 3 0 c[i][0] c[i] c i 0 int t = c[(i + 1) % 3][1] - c[i][1]; t c[(i + 1) % 3][1] - c[i][1] c[(i + 1) % 3][1] c[(i + 1) % 3] c (i + 1) % 3 (i + 1) i 1 3 1 c[i][1] c[i] c i 1 int u = c[(i + 1) % 3][2] - c[i][2]; u c[(i + 1) % 3][2] - c[i][2] c[(i + 1) % 3][2] c[(i + 1) % 3] c (i + 1) % 3 (i + 1) i 1 3 2 c[i][2] c[i] c i 2 if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			} s != t || t != u || u != s s != t || t != u || u != s s != t s t t != u t u u != s u s {
				System.out.println("No");
				return;
			} System.out.println("No") System.out.println System.out System System.out "No" return; System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	}
} public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import java.util.function.Consumer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		int c[][] = new int[3][3];

		for (int i = 0; i < 3; i++) {
			String str[] = br.readLine().split(" ");
			for (int j = 0; j < 3; j++) {
				c[i][j] = Integer.parseInt(str[j]);
			}
		}

		for (int i = 0; i < 3; i++) {
			int s = c[(i + 1) % 3][0] - c[i][0];
			int t = c[(i + 1) % 3][1] - c[i][1];
			int u = c[(i + 1) % 3][2] - c[i][2];

			if (s != t || t != u || u != s) {
				System.out.println("No");
				return;
			}
		}

		System.out.println("Yes");
	}
}
