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 sc = new Scanner(System.in);
		int nummax = sc.nextInt();
		String astring = sc.next();
		String bstring = sc.next();
		String cstring = sc.next();

		int ans = 0;

		for (int i =0;i < nummax; i++) {

			if(!astring.substring(i,i+1).equals(bstring.substring(i,i+1))){
				ans++;
			}
			if(!astring.substring(i,i+1).equals(cstring.substring(i,i+1)) &&
					!bstring.substring(i,i+1).equals(cstring.substring(i,i+1)) 	){
				ans++;
			}
		}
		System.out.println(ans);
	    sc.close();

	}

}