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][100005];
int main(){
	int n,ans=0;
	scanf("%d%s%s%s",&n,a[0],a[1],a[2]);
	for (int i=0;i<n;i++)
		if (a[0][i]==a[1][i]&&a[1][i]==a[2][i]) ans+=0;
		else if (a[0][i]==a[1][i]||a[0][i]==a[2][i]||a[1][i]==a[2][i]) ans+=1;
		else ans+=2;
	printf("%d\n",ans);
}