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();
    sc.nextLine();
    String A = sc.nextLine();
    String B = sc.nextLine();
    String C = sc.nextLine();
    char[] cha = A.toCharArray();
    char[] chb = B.toCharArray();
    char[] chc = C.toCharArray();
    int sum = 0;
    for (int i = 0; i < N; i++) {
      int[] mat = new int[26];
      mat[cha[i] - 'a']++;
      mat[chb[i] - 'a']++;
      mat[chc[i] - 'a']++;

      int max = 0;
      for (int j = 0; j < mat.length; j++) {
        max = Math.max(max, mat[j]);
      }
      sum += (3 - max);
    }
    System.out.println(sum);
  }
}
