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;
char a[3][101];
int i,j,n,ans;
int main()
{
	cin>>n;
	for(i=0;i<3;i++)cin>>a[i];
	for(i=0;i<n;i++)
	 {if(a[0][i]!=a[1][i]&&a[1][i]!=a[2][i]&&a[0][i]!=a[2][i])ans+=2;
	  else if(!(a[0][i]==a[1][i]&&a[1][i]==a[2][i]))ans++;
	 }
	cout<<ans<<endl;
}