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<stdio.h>
int main(void) {
	int n, i, sum = 0, x;
	char a[100], b[100], c[100];
	char k;
	scanf("%d %s %s %s", &n, a, b, c);
	for (i = 0; i < n; i++) {
		x = 0;
		if (b[i] == c[i] && a[i] == b[i]);
		else if(a[i]==b[i]||b[i]==c[i]||a[i]==c[i])x++;
		else x += 2;
		sum += x;
	}
	printf("%d\n", sum);
}
