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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        B solver = new B();
        solver.solve(1, in, out);
        out.close();
    }

    static class B {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            // 入力
            int N = Integer.parseInt(in.next());
            String A = in.next();
            String B = in.next();
            String C = in.next();
            int ans = 0;

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

            // 出力
            out.println(ans);

        }

    }
}

