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){
      	//データ取り込み
		Scanner sc = new Scanner(System.in);
 
		int N = sc.nextInt();
      	String A = sc.next();
      	String B = sc.next();
      	String C = sc.next();
      	StringBuffer chA =new StringBuffer(A);
      	StringBuffer chB =new StringBuffer(B);
      	StringBuffer chC =new StringBuffer(C);
		int cnt = 0;
      	for(int i=0;i<N;i++){
        	if(chA.charAt(i) == chB.charAt(i) && chB.charAt(i) == chC.charAt(i)){
            	cnt += 0;
            }else if(chA.charAt(i) == chB.charAt(i) ||
                     chB.charAt(i) == chC.charAt(i) ||
                     chC.charAt(i) == chA.charAt(i)){
              	cnt += 1;
            }else{
            	cnt += 2;
            }
        }
        System.out.println(cnt);
    }
}