import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int a[] = new int [3];
		int b[] = new int [3];
		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();
			}
		}

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int a[] = new int [3];
		int b[] = new int [3];
		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();
			}
		}

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

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

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	} main {
		Scanner scan = new Scanner(System.in);
		int a[] = new int [3];
		int b[] = new int [3];
		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();
			}
		}

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) int a[] = new int [3]; a new int [3] 3 int b[] = new int [3]; b new int [3] 3 int c[][] = new int [3][3]; c new int [3][3] 3 3 for ( int i = 0; i < 3; i++) {
			for ( int j= 0;j < 3; j++) {
				c[i][j] = scan.nextInt();
			}
		} 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] = scan.nextInt();
			}
		} {
			for ( int j= 0;j < 3; j++) {
				c[i][j] = scan.nextInt();
			}
		} for ( int j= 0;j < 3; j++) {
				c[i][j] = scan.nextInt();
			} int j= 0; int j= 0; j 0 j < 3 j 3 j++ j++ j {
				c[i][j] = scan.nextInt();
			} {
				c[i][j] = scan.nextInt();
			} c[i][j] = scan.nextInt() c[i][j] c[i] c i j scan.nextInt() scan.nextInt scan int temp1 = c[0][1]-c[0][2]; temp1 c[0][1]-c[0][2] c[0][1] c[0] c 0 1 c[0][2] c[0] c 0 2 int temp2 = c[1][1]-c[1][2]; temp2 c[1][1]-c[1][2] c[1][1] c[1] c 1 1 c[1][2] c[1] c 1 2 int temp3 = c[2][1]-c[2][2]; temp3 c[2][1]-c[2][2] c[2][1] c[2] c 2 1 c[2][2] c[2] c 2 2 int temp4 = c[0][0]-c[0][1]; temp4 c[0][0]-c[0][1] c[0][0] c[0] c 0 0 c[0][1] c[0] c 0 1 int temp5 = c[1][0]-c[1][1]; temp5 c[1][0]-c[1][1] c[1][0] c[1] c 1 0 c[1][1] c[1] c 1 1 int temp6 = c[2][0]-c[2][1]; temp6 c[2][0]-c[2][1] c[2][0] c[2] c 2 0 c[2][1] c[2] c 2 1 boolean ans = true; ans true if (temp1 != temp2) {
			ans = false;
		} temp1 != temp2 temp1 temp2 {
			ans = false;
		} ans = false ans false if (temp1 != temp3) {
			ans = false;
		} temp1 != temp3 temp1 temp3 {
			ans = false;
		} ans = false ans false if (temp4 != temp5) {
			ans = false;
		} temp4 != temp5 temp4 temp5 {
			ans = false;
		} ans = false ans false if (temp4 != temp6) {
			ans = false;
		} temp4 != temp6 temp4 temp6 {
			ans = false;
		} ans = false ans false if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		} ans {
			System.out.println("Yes");
		} System.out.println("Yes") System.out.println System.out System System.out "Yes" {
			System.out.println("No");
		} System.out.println("No") System.out.println System.out System System.out "No" String args[] args public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int a[] = new int [3];
		int b[] = new int [3];
		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();
			}
		}

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}
} public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int a[] = new int [3];
		int b[] = new int [3];
		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();
			}
		}

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}
} Main
import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner scan = new Scanner(System.in);
		int a[] = new int [3];
		int b[] = new int [3];
		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();
			}
		}

		int temp1 = c[0][1]-c[0][2];
		int temp2 = c[1][1]-c[1][2];
		int temp3 = c[2][1]-c[2][2];

		int temp4 = c[0][0]-c[0][1];
		int temp5 = c[1][0]-c[1][1];
		int temp6 = c[2][0]-c[2][1];

		boolean ans = true;
		if (temp1 != temp2) {
			ans = false;
		}
		if (temp1 != temp3) {
			ans = false;
		}

		if (temp4 != temp5) {
			ans = false;
		}
		if (temp4 != temp6) {
			ans = false;
		}



		if(ans) {
			System.out.println("Yes");
		} else {
			System.out.println("No");
		}

	}
}