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.*;
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int N = sc.nextInt();
    char[] A = sc.next().toCharArray();
    char[] B = sc.next().toCharArray();
    char[] C = sc.next().toCharArray();
    int cnt = 0;
    for(int i=0; i<N; i++){
      if(A[i]==B[i] && A[i]==C[i]){
        ;
      }else if(A[i]!=B[i] && A[i]!=C[i] && B[i]!=C[i]){
        cnt += 2;
      }else{
        cnt++;
      }
    }
    System.out.print(cnt);
  }
}
