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.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {
	public static void main(String args[]) {
		Scanner sc = new Scanner(System.in);

		int N = sc.nextInt();
		String[] A = sc.next().split("");
		String[] B = sc.next().split("");
		String[] C = sc.next().split("");

		int result = 0;
		for (int i = 0; i < N; i++) {
			Map<String, Integer> map = new HashMap<String, Integer>();
			map.put(A[i], 0);
			if (map.get(B[i]) == null) {
				map.put(B[i], 0);
			} else {
				map.put(B[i], map.get(B[i]) + 1);
			}

			if (map.get(C[i]) == null) {
				map.put(C[i], 0);
			} else {
				map.put(C[i], map.get(C[i]) + 1);
			}

			if (map.size() == 3) {
				result += 2;
			} else if (map.size() == 2) {
				result++;
			}
		}

		System.out.println(result);

	}
}