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[105], B[105], C[105];
int main(){
	int N; scanf("%d",&N);
	scanf("%s%s%s",A,B,C);
	int ans = 0;
	for(int i=0; i<N; ++i){
		if(A[i]==B[i] && B[i]==C[i]) continue;
		else if(A[i]==B[i] || B[i]==C[i] || C[i]==A[i]) ++ans;
		else ans += 2;
	}
	printf("%d\n",ans);
	return 0;
}