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) {
		Main m = new Main();
		m.run();
	}

	Scanner sc = new Scanner(System.in);

	void run() {
		int n = sc.nextInt();
		
		String a = sc.next();
		String b = sc.next();
		String c = sc.next();
		int ans = 0;
		for(int i = 0; i < n; i++){
			ans += check(a.charAt(i), b.charAt(i), c.charAt(i));
		}
		System.out.println(ans);
	}
	
	int check(char a, char b , char c){
		if(a == b && a == c){
			return 0;
		}
		
		if(a == b || a == c || b == c){
			return 1;
		}
		
		return 2;		
	}
}
