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.*;

public class Main {

  public static void main(String[] args) throws IOException {

    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    
    String[] in = br.readLine().split(" ");
    int n = Integer.parseInt(in[0]);

    String a = br.readLine();
    String b = br.readLine();
    String c = br.readLine();

    br.close();

    int ans = 0;

    for(int i = 0; i < n; i++){
      int sameNum = 0;
      if(a.charAt(i) == b.charAt(i)) sameNum++;
      if(b.charAt(i) == c.charAt(i)) sameNum++;
      if(c.charAt(i) == a.charAt(i)) sameNum++;

      int add = 0;
      if(sameNum == 0) add = 2;
      if(sameNum == 1) add = 1;

      ans += add;
    }

    System.out.println(ans);
  }
}