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();
    String a = sc.next();
    String b = sc.next();
    String c = sc.next();
    int ans = 0;

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

    System.out.println(ans);

  }
}