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>
using namespace std;
int main(){
char a[1005];
char b[1005];
char c[1005];
	int n;
	cin>>n;
			cin>>a>>b>>c;

	int cnt=0;
	for(int j=0;j<n;j++){
		if(a[j]==b[j]&&a[j]==c[j]&&b[j]==c[j])
			cnt+=0;
		else if(a[j]!=b[j]&&a[j]!=c[j]&&b[j]!=c[j])
			cnt+=2;
		else 
			cnt+=1;
	}
	cout<<cnt<<endl;

}