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[]) {
        try (Scanner in = new Scanner(System.in)) {
            int N = in.nextInt();
            String A = in.next();
            String B = in.next();
            String C = in.next();

            int count = 0;
            for (int i = 0; i < N; i++) {
                char a = A.charAt(i);
                char b = B.charAt(i);
                char c = C.charAt(i);
                boolean ab = a == b;
                boolean bc = b == c;
                boolean ca = c == a;
                if (ab) {
                    if (bc) {
                        continue;
                    } else {
                        count++;
                        continue;
                    }
                } else {
                    if (bc || ca) {
                        count++;
                        continue;
                    } else {
                        count++;
                        count++;
                        continue;
                    }
                }
            }

            System.out.println(count);
        }
    }
}
