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.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.next());
        StringBuilder A = new StringBuilder(N);
        StringBuilder B = new StringBuilder(N);
        StringBuilder C = new StringBuilder(N);
        A.append(sc.next());
        B.append(sc.next());
        C.append(sc.next());
        sc.close();
        
        int cnt = 0;
        for (int i=0; i<N; i++) {
            if (A.charAt(i)==B.charAt(i) & A.charAt(i)==C.charAt(i)) {
                //non
            } else if (A.charAt(i)!=B.charAt(i) & A.charAt(i)!=C.charAt(i) & B.charAt(i)!=C.charAt(i)) {
                cnt+=2;
            } else {
                cnt++;
            }
        }
        System.out.println(cnt);
    }
}