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.*;

public class Main {
    public static void main(String[] args) {
        final Scanner sc = new Scanner(System.in);
        int ans = 0;
        int n = sc.nextInt();
        String a = sc.next();
        String b = sc.next();
        String c = sc.next();
        for (int i = 0; i < n; i++) {
            HashSet<Character> se = new HashSet<Character>();
            se.add(a.charAt(i));
            se.add(b.charAt(i));
            se.add(c.charAt(i));
            ans += (se.size() - 1);
        }
        System.out.println(ans);
        sc.close();
    }
}