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();
      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]&&b[i]!=c[i]&&c[i]!=a[i])cnt+=2;
        else if(a[i]==b[i]&&b[i]==c[i]){}
        else cnt++;
      }
      System.out.println(cnt);
    }
}
