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.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(System.out);
        int N = Integer.parseInt(br.readLine());
        String A = br.readLine();
        String B = br.readLine();
        String C = br.readLine();
        int ans = 0;
        for (int i = 0; i < N; i++) {
            char a = A.charAt(i);
            char b = B.charAt(i);
            char c = C.charAt(i);
            if (a == b && b == c) {
                // do nothing
            } else if (a == b || b == c || c == a) {
                ans++;
            } else {
                ans += 2;
            }
        }
        out.println(ans);
        out.close();
    }
}
