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;

int main(){
  int n;
  cin >> n;

  string a,b,c;
  cin >> a >> b >> c;

  int ret = 0;
  for(int i = 0;i < n;i++){
    set<int> st;
    st.insert(a[i]-'a');
    st.insert(b[i]-'a');
    st.insert(c[i]-'a');
    ret += st.size() - 1;
  }
  cout << ret << endl;
}
