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 = Integer.parseInt(sc.nextLine());
		String a = sc.nextLine();
		String b = sc.nextLine();
		String c = sc.nextLine();
		
		int op = 0;
		
		for (int i = 0; i < n; i++) {
			final char chA = a.charAt(i);
			final char chB = b.charAt(i);
			final char chC = c.charAt(i);
			
			final boolean abMatch = chA == chB;
			final boolean acMatch = chA == chC;
			final boolean bcMatch = chB == chC;
			
			if (abMatch && acMatch) {
				// do nothing
			} else if (abMatch || acMatch || bcMatch) {
				op += 1;
			} else {
				op += 2;
			}
		}
		
		System.out.println(op);
	}

}