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 scanner = new Scanner(System.in);

		int n = scanner.nextInt();
		String a = scanner.next();
		String b = scanner.next();
		String c = scanner.next();
		int count = 0;

		for (int i = 0; i < n; i++) {
			if (a.charAt(i) == b.charAt(i)) {
				if (a.charAt(i) == c.charAt(i)) {

				} else {
					count++;
				}
			} else {
				if (a.charAt(i) == c.charAt(i)) {
					count++;
				} else {
					if (b.charAt(i) == c.charAt(i)) {
						count++;
					} else {
						count += 2;
					}
				}
			}
		}
		System.out.print(count);

		scanner.close();
	}

}
