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.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		// 標準入力
		Scanner scanner = new Scanner(System.in);
		String n = scanner.nextLine();
		String a = scanner.nextLine();
		String b = scanner.nextLine();
		String c = scanner.nextLine();

		int nInt = Integer.parseInt(n);

		int count = 0;

		for (int i=0; i<nInt; i++) {
			char charA = a.charAt(i);
			char charB = b.charAt(i);
			char charC = c.charAt(i);

			List<Character> listA = new ArrayList<Character>(Arrays.asList(charA, charB, charC));
	        List<Character> listB = new ArrayList<Character>(new HashSet<>(listA));

	        count += listB.size();
		}

		count -= nInt;

		System.out.println(count);

	}
}
