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();
        String B = sc.next();
        String C = sc.next();
        int ans = 0;
        for(int i = 0; i < N; i++){
            if(A.charAt(i) != B.charAt(i) && A.charAt(i) != C.charAt(i) && B.charAt(i) != C.charAt(i)) ans += 2;
            else if(A.charAt(i) != B.charAt(i) && A.charAt(i) != C.charAt(i) && B.charAt(i) == C.charAt(i)) ans += 1;
            else if(A.charAt(i) != B.charAt(i) && A.charAt(i) == C.charAt(i) && B.charAt(i) != C.charAt(i)) ans += 1;
            else if(A.charAt(i) == B.charAt(i) && A.charAt(i) != C.charAt(i) && B.charAt(i) != C.charAt(i)) ans += 1;
        }

        System.out.println(ans);
        sc.close();
    }

}
