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.*;

class Main {
public static void main(String args[]) {
  Scanner sc = new Scanner(System.in);
  
  int N = sc.nextInt();
  String A = sc.next();
  String B = sc.next();
  String C = sc.next();
  
  int sum = 0;
  for(int i = 0;i < N;i++) {
    if(A.charAt(i) == B.charAt(i)) {
      if(A.charAt(i) == C.charAt(i)) {
      } else {
        sum += 1;
      }
    } else {
      if(B.charAt(i) == C.charAt(i)) {
        sum += 1;
      } else {
        if(A.charAt(i) == C.charAt(i)) {
        	sum += 1;
        } else {
          sum += 2;
        }
      }
    }
  }
  
  System.out.println(sum);
}
}