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) throws Exception {
    Scanner scanner = new Scanner(System.in);
    try {
      int n = scanner.nextInt();
      String a = scanner.next();
      String b = scanner.next();
      String c = scanner.next();

      int ans = 0;
      for (int i = 0; i < n; i++) {
        ans += solve(a.charAt(i), b.charAt(i), c.charAt(i));
      }
      System.out.print(ans);
    } finally {
      scanner.close();
    }
  }

  private static int solve(int a, int b, int c) {
    int ans = 2;
    if (a == b) ans--;
    if (a == c) ans--;
    if (b == c) ans--;
    if (ans < 0) ans = 0;
    return ans;
  }
}
