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.IOException;
import java.io.InputStreamReader;

public class Main
{

  public static void main(String[] args) throws IOException
  {
    BufferedReader r = new BufferedReader(new InputStreamReader(System.in), 1);
    String s = r.readLine();
    int n = Integer.parseInt(s);
    String a = r.readLine();
    String b = r.readLine();
    String c = r.readLine();
    int z = 0;
    for(int i = 0; i < n; i++)
    {
      if(a.charAt(i) == b.charAt(i) && a.charAt(i) == c.charAt(i))
      {
        z += 0;
      }
      else if(a.charAt(i) == b.charAt(i) || a.charAt(i) == c.charAt(i) || c.charAt(i) == b.charAt(i))
      {
        z += 1;
      }
      else
      {
        z += 2;
      }
    }

    System.out.println(z);
  }

}
