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 <iostream>
#include <string>
using namespace std;
int main() {
  int N;
  string s, t, u;
  cin >> N;
  cin >> s;
  cin >> t;
  cin >> u;
  int ret = 0;
  for (int i=0; i<N; i++) {
    if (s[i] == t[i] && t[i] == u[i]) continue;
    if (s[i] == t[i] || t[i] == u[i] || u[i] == s[i]) ret++;
    else ret += 2;
  }
  cout << ret << endl;
}