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;

class Main {

  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int n = scanner.nextInt();
    String[] strings = new String[3];
    strings[0] = scanner.next();
    strings[1] = scanner.next();
    strings[2] = scanner.next();
    scanner.close();
    int ans = 0;
    for (int i = 0; i < n; i++) {
      int[] counts = new int[3];
      for (int j = 0; j < 3; j++) {
        for (int k = 0; k < 3; k++) {
          if (strings[j].charAt(i) != strings[k].charAt(i)) {
            counts[j]++;
          }
        }
      }
      int min = counts[0];
      if (counts[1] < min) {
        min = counts[1];
      }
      if (counts[2] < min) {
        min = counts[2];
      }
      ans += min;

    }
    System.out.println(ans);
  }

}
