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(); // 文字列の長さ
	    String A = sc.next(); 
		String B = sc.next(); 
		String C = sc.next(); 

        int returnCount = 0;
        for (int i = 0; i < N; i++) {
            char cA = A.charAt(i);
            char cB = B.charAt(i);
            char cC = C.charAt(i);
            int count = 0;
            if (cA != cB) count++;
            if (cB != cC) count++;
            if (cC != cA) count++;
            
            if (count == 3) {
                returnCount += 2;
            } else if (count == 2) {
                returnCount += 1;
            }
        }
		
        System.out.println(returnCount);
	}
}