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.Collections;
import java.util.HashMap;
import java.util.Scanner;

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();
        String[] ss = {A, B, C};

        int ans = 0;
        for(int i = 0; i < N; i++) {
            HashMap<Character, Integer> counts = new HashMap<>();
            for(int k = 0; k < ss.length; k++) {
                char c = ss[k].charAt(i);
                counts.put(c, counts.getOrDefault(c, 0) + 1);
            }
            int maxNum = Collections.max(counts.values());
            ans += (ss.length - maxNum);
        }

        System.out.println(ans);
    }
}
