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 scn = new Scanner(System.in);
		int N = scn.nextInt();
		scn.nextLine();
		char[] A = scn.nextLine().toCharArray();
		char[] B = scn.nextLine().toCharArray();
		char[] C = scn.nextLine().toCharArray();

		int ans = 0;
		for(int i = 0;i < N;i++) {
			char a,b,c;
			a = A[i];
			b = B[i];
			c = C[i];

			if(a != b) {
				if(a!=c) {
					if(b != c) {
						ans+=2;
					}else {
						ans++;
					}
				}else {
					ans++;
				}
			}else {
				if(a != c) {
					ans++;
				}else {

				}
			}
		}
		System.out.println(ans);

	}

}
