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 main() {
	int N, count = 0;
	string A, B, C;
	cin >> N >> A >> B >> C;
	for (int i = 0; i < N; i++) {
		if (A[i] == B[i] && B[i] == C[i]) count += 0;
		else if (A[i] == B[i] || B[i] == C[i] || C[i] == A[i]) count += 1;
		else count += 2;
	}
	cout << count;
}