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;
    string a,b,c;
    cin>>n>>a>>b>>c;

    int ans = 0;
    for(int i=0; i<n; i++) {
        if(a.at(i)!=b.at(i) && b.at(i)!=c.at(i) && c.at(i)!=a.at(i)) ans += 2;
        else if(a.at(i)!=b.at(i) || b.at(i)!=c.at(i)) ans++;
    }

    cout<<ans<<endl;

    return 0;
}