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) {
    Scanner scan = new Scanner(System.in);

    int N = scan.nextInt();
    String A = scan.next();
    String B = scan.next();
    String C = scan.next();
    String choiceOfA = "0";
    String choiceOfB = "0";
    String choiceOfC = "0";
    int ans = 0;
    for (int i = 0;i<N ;i++ ) {
      choiceOfA = A.substring(i,i+1);
      choiceOfB = B.substring(i,i+1);
      choiceOfC = C.substring(i,i+1);
      if (!choiceOfA.equals(choiceOfB) && !choiceOfB.equals(choiceOfC) && !choiceOfC.equals(choiceOfA)) {
        ans+=2;
      }else if((choiceOfA.equals(choiceOfB) && !choiceOfB.equals(choiceOfC) || (choiceOfB.equals(choiceOfC) && !choiceOfC.equals(choiceOfA)) || (choiceOfC.equals(choiceOfA) && !choiceOfA.equals(choiceOfB)))) ans++;
    }
    System.out.println(ans);
  }
}
