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;

int N;
char A[110], B[110], C[110];

int main(){
	scanf("%d%s%s%s",&N, A, B, C);
	int ret = 0;

	for(int i=0;i<N;++i){
		char a = A[i], b = B[i], c = C[i];
		if(a == b && b == c && c == a) ret+=0;
		else if (a == b || b == c || c == a) ret+=1;
		else ret+=2;
	}
	printf("%d\n",ret);
	return 0;
}
