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 <iostream>
#include <cstdio>
using namespace std;

int main()
{
int n,i,cnt=0;
cin >> n;
char a[n],b[n],c[n];
cin >> a;
cin >> b;
cin >> c;

for(i=0;i<n;i++){
if(a[i]!=b[i] && a[i]!=c[i] && b[i]!=c[i]){
cnt=cnt+2;
}else if(a[i]!=b[i] || a[i]!=c[i] || b[i]!=c[i]){
cnt=cnt+1;
}
}

cout << cnt << endl;

    return 0;
}