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);
	long a=scan.nextInt();
	String b=scan.next();
	String c=scan.next();
	String d=scan.next();
int ans=0;
	for(int i=0;i<a;i++) {
		char x=b.charAt(i);
		char y=c.charAt(i);
		char z=d.charAt(i);
		if(x==y&&y==z) {
		}
		else if(x==y||y==z||x==z) {
			ans++;
		}
		else {
			ans+=2;
		}
	}
	System.out.println(ans);
	}
}