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();
		char[] a = sc.next().toCharArray();
		char[] b = sc.next().toCharArray();
		char[] c = sc.next().toCharArray();
		int count = 0;
		for(int i = 0; i < n; i ++) {
			if(a[i] == b[i]) {
				if(a[i] == c[i]) {

				}else{
					count ++;
				}
			}else{
				if(a[i] == c[i]) {
					count ++;
				}else if(b[i] == c[i]) {
					count ++;
				}else {
					count += 2;
				}
			}
		}
		System.out.println(count);

	}
}