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>
typedef long long ll;
using namespace std;
int main(){
    cin.tie(NULL); cout.tie(NULL);
    ios_base:: sync_with_stdio(false);
    ll n;cin>>n;
    string s,t,u;cin>>s>>t>>u;
    ll ans = 0;
    for(ll i=0;i<n;i++){
        set<char> st={s[i],t[i],u[i]};
        ans+=st.size()-1;
    }
    cout<<ans;
}