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) {
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int[][] a = new int[n][26];
    for(int i = 0; i < 3; i++) {
      String s = sc.next();
      for(int j = 0; j < n; j++) {
        int t = s.charAt(j) - 'a';
        a[j][t]++;
      }
    }
    int ans = 0;
    for(int i = 0; i < n; i++) {
      int m = 0;
      for(int j = 0; j < 26; j++) {
        m = Math.max(m, a[i][j]);
      }
      ans += (3 - m);
    }
    System.out.println(ans);
  }
}