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();
		String a = sc.next();
		String b = sc.next();
		String c = sc.next();
		
		//変更必要回数をカウント
		int count = 0;
		for(int i=0; i<n; i++) {
			boolean aIsB = a.charAt(i) == b.charAt(i);
			boolean bIsC = b.charAt(i) == c.charAt(i);
			boolean cIsA = c.charAt(i) == a.charAt(i);
			
			if(aIsB==false && bIsC==false && cIsA==false) {
				count = count+2;
			} else if(aIsB==false && bIsC==false && cIsA==true
					||aIsB==false && bIsC==true && cIsA==false
					||aIsB==true && bIsC==false && cIsA==false) {
				count = count+1;
			}	
		}
		System.out.print(count);
	}
}