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>
#define rep(i, n) for(int i = 0; i < n; i++)
using namespace std;

signed main(void)
{
	int n;
	string a, b, c;
	cin >> n >> a >> b >> c;
	long long ans = 0;
	rep(i, n)
	{
		map<char, int> mp;
		mp[a[i]]++;
		mp[b[i]]++;
		mp[c[i]]++;
		ans +=  mp.size() - 1;
	}
	cout << ans << endl;
	return 0;
}
