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 dir_c(char a,char b,char c){
  if(a==b && b==c) return 0;
  if((a==c&&a!=b)||(b==c&&b!=a)||(a==b&&a!=c)) return 1;
  return 2;
}
int main(){
 int n,cnt=0;
 string a, b,c;
 cin >> n >> a >> b >> c;
 for(int i=0;i<n;i++){
   cnt += dir_c(a[i],b[i],c[i]);
 }
 cout << cnt << endl;
}
