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.Scanner;

public class Main {
	public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String line = in.nextLine();
        int n = Integer.parseInt(line);
        String s1 = in.nextLine();
        String s2 = in.nextLine();
        String s3 = in.nextLine();
        in.close();

        int ans = 0;
        for (int i = 0 ; i < n ; i++) {
        	if (s1.charAt(i) == s2.charAt(i) && s1.charAt(i) == s3.charAt(i)) {
        		;
        	} else if (s1.charAt(i) == s2.charAt(i)) {
        		ans = ans + 1;
        	} else if (s1.charAt(i) == s3.charAt(i)) {
        		ans = ans + 1;
        	} else if (s3.charAt(i) == s2.charAt(i)) {
        		ans = ans + 1;
        	} else {
        		ans = ans + 2;
        	}
        }
        System.out.println(ans);
    }
}