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;
signed main(){
  int a,b=0,d=0;
  string c[3];
  cin>>a;
  for(int i=0;i<3;i++) cin>>c[i];
  for(int i=0;i<a;i++){
    b=0;
    if(c[0][i]==c[1][i]);
    else b++;
    if(c[0][i]==c[2][i]);
    else b++;
    if(c[1][i]==c[2][i]);
    else b++;
    d=(b+1)/2+d;
    }
  cout<<d<<"\n";
  }
