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 scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        String a = scanner.next();
        String b = scanner.next();
        String c = scanner.next();
        int num = 0;
        for (int i = 0; i < n; ++i) {
            char c1 = a.charAt(i);
            char c2 = b.charAt(i);
            char c3 = c.charAt(i);
            if (c1 == c2 && c2 == c3) {
                continue;
            } else if (c1 == c2 || c2 == c3 || c1 == c3) {
                ++num;
            } else {
                num += 2;
            }
        }
        System.out.println(num);
    }
}
