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.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner input = new Scanner(new BufferedReader(new InputStreamReader(System.in)));
		int N = input.nextInt();
		input.nextLine();
		String A = input.nextLine();
		String B = input.nextLine();
		String C = input.nextLine();

		int count = 0;
		for (int i=0;i<N;i++) {
			char c1 = A.charAt(i);
			char c2 = B.charAt(i);
			char c3 = C.charAt(i);

			if (c1 == c2 && c2 == c3) {
				// do nothing
			}else if (c1 == c2 && c2 != c3) {
				count++;
			} else if (c1 != c2 && c2 == c3) {
				count++;
			} else if (c1 == c3 && c3 != c2) {
				count++;
			} else {
				count += 2;
			}
		}

		System.out.println(count);
	}

}
