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 scan = new Scanner(System.in);
		int p = scan.nextInt();
		String a = scan.next();
		String b = scan.next();
		String c = scan.next();
		int cou = 0;
		for(int i=0;i<p;i++){
			if((a.charAt(i)==b.charAt(i))&&(b.charAt(i)==c.charAt(i))){
				cou+=0;
			}else if(a.charAt(i)==b.charAt(i)){
				cou++;
			}else if(b.charAt(i)==c.charAt(i)){
				cou++;
			}else if(a.charAt(i)==c.charAt(i)){
				cou++;
			}else{
				cou+=2;
			}
		}
		System.out.println(cou);
	}
}