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;
const int N=100+10;
int n;
char A[N],B[N],C[N];

int main()
{
	scanf("%d",&n);
	scanf("%s%s%s",A+1,B+1,C+1);
	int ans=0;
	for (int i=1;i<=n;i++) {
		if (A[i]==B[i] && B[i]==C[i]) ans+=0;
		else if (A[i]!=B[i] && A[i]!=C[i] && B[i]!=C[i]) ans+=2;
		else ans+=1;
	}
	cout<<ans;
	return 0;
}