codeforces 978B

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,i,c=0,ans=0;
    cin>>n;
    string str;
    cin>>str;
        for(i=0; i<n; i++)
        {
          if(str[i]=='x' && str[i+1]=='x' && str[i+2]=='x')
                    c++;
        }
        cout<<c<<endl;


}