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
// B - Touitsu
#include <bits/stdc++.h>
using namespace std;
#define rp(i,s,e) for(int i=(s);i<(e);++i)
#define rpz(i,e) rp(i,0,e)

int main(){
	int N; cin>>N;
	string A,B,C; cin>>A>>B>>C;
	int count = 0;
	rpz(i, N) count += set<int>{A[i],B[i],C[i]}.size() - 1;
	cout<< count <<endl;
}