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.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		String A = sc.next();
		String B = sc.next();
		String C = sc.next();

		int count=0;
		for(int i=0;i<N;i++) {
			char a = A.charAt(i);
			char b = B.charAt(i);
			char c = C.charAt(i);
			if(a==b && a==c) {
				//nothing
			}else if(a==b || b ==c || a==c) {
				count++;
			}else {
				count++;
				count++;
			}
		}
		System.out.println(count);
	
	
	}
}
