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) {

        final Scanner scanner = new Scanner(System.in);
        final int n = scanner.nextInt();
        scanner.nextLine(); // empty string
        final String a = scanner.nextLine();
        final String b = scanner.nextLine();
        final String c = scanner.nextLine();

        int result = 0;
        for (int idx = 0; idx < n; idx++) {

            final char charInA = a.charAt(idx);
            final char charInB = b.charAt(idx);
            final char charInC = c.charAt(idx);

            if (charInA == charInB && charInB == charInC) {
                continue;
            } else if (charInA == charInB || charInB == charInC || charInC == charInA) {
                result++;
            } else {
                result += 2;
            }

        }

        System.out.println(result);

    }

}
