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 n = sc.nextInt();
		String a = sc.next();
		String b = sc.next();
		String c = sc.next();

		StringBuilder as = new StringBuilder();
		StringBuilder bs = new StringBuilder();
		StringBuilder cs = new StringBuilder();

		as.append(a);
		bs.append(b);
		cs.append(c);

		int count = 0;

		if(a.equals(b)&&a.equals(c)) {
			System.out.println(count);
		}
		else {
			for(int i = 0; i<n; i++) {
				if(as.charAt(i) == bs.charAt(i)) {
					if(as.charAt(i) == cs.charAt(i)) {
						continue;
					}
					else {
						cs.setCharAt(i, as.charAt(i));
						count++;
					}
				}else if(as.charAt(i) == cs.charAt(i)) {
					bs.setCharAt(i, as.charAt(i));
					count++;
				}
				else if(bs.charAt(i) == cs.charAt(i)) {
					as.setCharAt(i, bs.charAt(i));
					count++;
				}else {
					cs.setCharAt(i, as.charAt(i));
					bs.setCharAt(i, as.charAt(i));
					count+=2;
				}
			}
			System.out.println(count);
		}

	}

}