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();
        char[] A = sc.next().toCharArray();
        char[] B = sc.next().toCharArray();
        char[] C = sc.next().toCharArray();
        int counter = 0;
        for (int i = 0; i < N; i++) {
            if (A[i] == B[i] && B[i] == C[i]) {

            } else if (A[i] != B[i] && B[i] != C[i] && C[i] != A[i]) {
                counter += 2;
            } else counter++;
        }
        System.out.println(counter);
    }
}
