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.Arrays;
import java.util.HashSet;
import java.util.Scanner;

public class Main {

	static Scanner in = new Scanner(System.in);

	public static void main(String[] args) {
		int N = in.nextInt();
		String A = in.next();
		String B = in.next();
		String C = in.next();

		int change = 0;
		for (int i = 0;i < N; i++) {
			char ac = A.charAt(i);
			char bc = B.charAt(i);
			char cc = C.charAt(i);
			HashSet<Character> set = new HashSet<Character>(Arrays.asList(ac, bc, cc));
			change += set.size() - 1;
		}
		System.out.println(change);
	}
}
