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();
				String A = sc.next();
				char achar[] =A.toCharArray();
				String B = sc.next();
				char bchar[] = B.toCharArray();
				String C = sc.next();
				char cchar[] = C.toCharArray();
				
				int counter = 0;
				for (int i = 0; i<N; i++) {
					if(achar[i] == bchar[i]&&bchar[i] ==cchar[i])  //3文字同じ
						continue;
					else if(achar[i] ==bchar[i]||achar[i] == cchar[i]||bchar[i] == cchar[i]) //2文字ごとおなじ
						counter++;
					else
						counter += 2;
				}
				
				System.out.println(counter);
			}
}
