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 sc = new Scanner(System.in);
        int n = sc.nextInt();
        char[] a = sc.next().toCharArray();
        char[] b = sc.next().toCharArray();
        char[] c = sc.next().toCharArray();

        int res = 0;

        for(int i=0; i<n; i++) {
            char x = a[i];
            char y = b[i];
            char z = c[i];
            if(x == y && y == z) continue;
            if(x == y || y == z || z == x) {
                res ++;
                continue;
            }
            res += 2;
        }

        System.out.println(res);
    }

}
