import java.util.*;
class Main
{
	public static void main(String[] args)
	{
		Scanner s = new Scanner(System.in);
		int[][] arr = new int[3][3];
		for(int i=0;i<3;i++)
		{
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		}

		int flag =0 ;
		for(int i =0 ;i<2;i++)
		{
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		}

		for(int i =0 ;i<2;i++)
		{
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		}
		if(flag != 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}
} import java.util.*; util.* java class Main
{
	public static void main(String[] args)
	{
		Scanner s = new Scanner(System.in);
		int[][] arr = new int[3][3];
		for(int i=0;i<3;i++)
		{
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		}

		int flag =0 ;
		for(int i =0 ;i<2;i++)
		{
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		}

		for(int i =0 ;i<2;i++)
		{
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		}
		if(flag != 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}
} Main public static void main(String[] args)
	{
		Scanner s = new Scanner(System.in);
		int[][] arr = new int[3][3];
		for(int i=0;i<3;i++)
		{
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		}

		int flag =0 ;
		for(int i =0 ;i<2;i++)
		{
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		}

		for(int i =0 ;i<2;i++)
		{
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		}
		if(flag != 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	} main {
		Scanner s = new Scanner(System.in);
		int[][] arr = new int[3][3];
		for(int i=0;i<3;i++)
		{
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		}

		int flag =0 ;
		for(int i =0 ;i<2;i++)
		{
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		}

		for(int i =0 ;i<2;i++)
		{
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		}
		if(flag != 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	} Scanner s = new Scanner(System.in); s new Scanner(System.in) int[][] arr = new int[3][3]; arr new int[3][3] 3 3 for(int i=0;i<3;i++)
		{
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		} int i=0; int i=0; i 0 i<3 i 3 i++ i++ i {
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		} {
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		} for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			} int j =0 ; int j =0 ; j 0 j<3 j 3 j++ j++ j {
				arr[i][j] = s.nextInt();
			} {
				arr[i][j] = s.nextInt();
			} arr[i][j] = s.nextInt() arr[i][j] arr[i] arr i j s.nextInt() s.nextInt s int flag =0 ; flag 0 for(int i =0 ;i<2;i++)
		{
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		} int i =0 ; int i =0 ; i 0 i<2 i 2 i++ i++ i {
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		} {
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		} if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1; (arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]) (arr[i][0] - arr[i][1]) arr[i][0] arr[i] arr i 0 arr[i][1] arr[i] arr i 1 (arr[i+1][0] - arr[i+1][1]) arr[i+1][0] arr[i+1] arr i+1 i 1 0 arr[i+1][1] arr[i+1] arr i+1 i 1 1 flag = 1 flag 1 if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1; (arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]) (arr[i][1] - arr[i][2]) arr[i][1] arr[i] arr i 1 arr[i][2] arr[i] arr i 2 (arr[i+1][1] - arr[i+1][2]) arr[i+1][1] arr[i+1] arr i+1 i 1 1 arr[i+1][2] arr[i+1] arr i+1 i 1 2 flag = 1 flag 1 for(int i =0 ;i<2;i++)
		{
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		} int i =0 ; int i =0 ; i 0 i<2 i 2 i++ i++ i {
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		} {
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		} if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1; (arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]) (arr[0][i] - arr[1][i]) arr[0][i] arr[0] arr 0 i arr[1][i] arr[1] arr 1 i (arr[0][i+1] - arr[1][i+1]) arr[0][i+1] arr[0] arr 0 i+1 i 1 arr[1][i+1] arr[1] arr 1 i+1 i 1 flag = 1 flag 1 if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1; (arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]) (arr[1][i] - arr[2][i]) arr[1][i] arr[1] arr 1 i arr[2][i] arr[2] arr 2 i (arr[1][i+1] - arr[2][i+1]) arr[1][i+1] arr[1] arr 1 i+1 i 1 arr[2][i+1] arr[2] arr 2 i+1 i 1 flag = 1 flag 1 if(flag != 0)
			System.out.println("No");
		else
			System.out.println("Yes"); flag != 0 flag 0 System.out.println("No") System.out.println System.out System System.out "No" System.out.println("Yes") System.out.println System.out System System.out "Yes" String[] args args
import java.util.*;
class Main
{
	public static void main(String[] args)
	{
		Scanner s = new Scanner(System.in);
		int[][] arr = new int[3][3];
		for(int i=0;i<3;i++)
		{
			for(int j =0 ;j<3;j++)
			{
				arr[i][j] = s.nextInt();
			}
		}

		int flag =0 ;
		for(int i =0 ;i<2;i++)
		{
			if((arr[i][0] - arr[i][1]) != (arr[i+1][0] - arr[i+1][1]))
				flag = 1;
			if((arr[i][1] - arr[i][2]) != (arr[i+1][1] - arr[i+1][2]))
				flag = 1;
		}

		for(int i =0 ;i<2;i++)
		{
			if((arr[0][i] - arr[1][i]) != (arr[0][i+1] - arr[1][i+1]))
				flag = 1;
			if((arr[1][i] - arr[2][i]) != (arr[1][i+1] - arr[2][i+1]))
				flag = 1;
		}
		if(flag != 0)
			System.out.println("No");
		else
			System.out.println("Yes");
	}
}
