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 scan = new Scanner(System.in);
          
        int n = scan.nextInt();
        String st[] = new String[3];
        
        st[0] = scan.next();
        st[1] = scan.next();
        st[2] = scan.next();
        
        int cnt = 0;
        
        for(int i = 0 ; i < n ; i++){
          
          if(st[0].substring(i,i+1).charAt(0) == st[1].substring(i,i+1).charAt(0) &&
             st[1].substring(i,i+1).charAt(0) == st[2].substring(i,i+1).charAt(0) ){
          }
          else if(st[0].substring(i,i+1).charAt(0) == st[1].substring(i,i+1).charAt(0) ||
             st[1].substring(i,i+1).charAt(0) == st[2].substring(i,i+1).charAt(0) ||
             st[0].substring(i,i+1).charAt(0) == st[2].substring(i,i+1).charAt(0) ){
            cnt++;
          }
          else
            cnt += 2;
        }
            
        System.out.println(cnt);
	  }
}