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
#include <stdio.h>

int main()
{
  char a[110], b[110], c[110];
  int n;
  
  scanf("%d%s%s%s", &n, a, b, c);
  int x = 0;
  for (int i = 0; i < n; ++i)
  {
    if (a[i] == b[i])
    {
      if (c[i] != a[i]) ++x;
    }
    else
    {
      if (c[i] == a[i] || c[i] == b[i]) ++x; else x += 2;
    }
  }
  printf("%d\n", x);
}