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.*;

public class Main {
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		char[] arrA = sc.next().toCharArray();
		char[] arrB = sc.next().toCharArray();
		char[] arrC = sc.next().toCharArray();
		int count = 0;
		for (int i = 0; i < n; i++) {
		    if(arrA[i] == arrB[i]) {
		        if (arrB[i] != arrC[i]) {
		            count++;
		        }
		    } else if (arrA[i] == arrC[i] || arrB[i] == arrC[i]) {
		        count++;
		    } else {
		        count += 2;
		    }
		}
		System.out.println(count);
	}
}
