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;
typedef long long ll;
ll n,a[114514],b[114514];
int main() {
	ll n;
	string a,b,c;
	ll cnt=0;
	cin>>n>>a>>b>>c;
	for(int i=0;i<n;i++){
		if(a[i]!=b[i]){
			if(b[i]!=c[i]){
				if(c[i]!=a[i])cnt+=2;
				else cnt++;
			}else cnt++;
		}else if(b[i]!=c[i])cnt++;
	}
	cout<<cnt<<endl;
	return 0;
}