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<bits/stdc++.h>
using namespace std;
typedef long long ll;

int main(){
  int n;
  cin >> n;
  
  string a,b,c;
  cin >> a >> b >> c;
  
  int ans = 0;
  for(int i=0; i<n; i++){
    if(a[i] == b[i] && b[i] == c[i]) continue;
    else if(a[i] == b[i] || b[i] == c[i] || c[i] == a[i]) ans++;
    else ans += 2;
  }

  cout << ans << endl;
}