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.ArrayList;
import java.util.Arrays;
import java.util.List;
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();

        int total = 0;

        for (int i = 0; i < n; i++) {
            if (a.charAt(i) == b.charAt(i) && b.charAt(i) == c.charAt(i)) {
                ;
            } else if (a.charAt(i) != b.charAt(i) && b.charAt(i) != c.charAt(i) && a.charAt(i) != c.charAt(i)) {
                total = total + 2;
            } else {
                total++;
            }
        }

        System.out.println(total);


    }

}





