You are given three strings A, B and C. Each of these is a string of length N consisting of lowercase English letters.

Our objective is to make all these three strings equal. For that, you can repeatedly perform the following operation:

* Operation: Choose one of the strings A, B and C, and specify an integer i between 1 and N (inclusive). Change the i-th character from the beginning of the chosen string to some other lowercase English letter.



What is the minimum number of operations required to achieve the objective?

Constraints

* 1 \leq N \leq 100
* Each of the strings A, B and C is a string of length N.
* Each character in each of the strings A, B and C is a lowercase English letter.

Input

Input is given from Standard Input in the following format:


N
A
B
C


Output

Print the minimum number of operations required.

Examples

Input

4
west
east
wait


Output

3


Input

9
different
different
different


Output

0


Input

7
zenkoku
touitsu
program


Output

13
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner stdIn=new Scanner(System.in);
		int N=stdIn.nextInt();
		String A=stdIn.next();
		String B=stdIn.next();
		String C=stdIn.next();
		char[]a=new char[N];
		char[]b=new char[N];
		char[]c=new char[N];
		int z=0,y=0;
		while(z<N){
			a[z]=A.charAt(z);
			b[z]=B.charAt(z);
			c[z]=C.charAt(z);
			if(a[z]==b[z]||a[z]==c[z])
				y++;
			else
				if(b[z]==c[z])
					y++;
				else
					y+=2;
			if(a[z]==b[z]&&a[z]==c[z])
				if(b[z]==c[z])
					y--;
			z++;
		}
		System.out.println(y);
	}

}