B. File Name

#include <bits/stdc++.h>

using namespace std ;
#define sz(s) int(s.size())
#define all(v) v.begin() , v.end()
#define imin INT_MIN
#define imax INT_MAX
typedef long long ll ;
#define Time cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " Secs" << "\n";
#define all(s) s.begin(), s.end()
#define cin(v) for (auto& i : v) cin >> i ;
#define pb(x) push_back(x)
#define getline(s) getline(cin >> ws, s)

void ABDEL3AL () {
    ios_base::sync_with_stdio(false); cin.tie(nullptr) , cout.tie(nullptr) ;
#ifndef ONLINE_JUDGE
    freopen("input.txt" , "r" , stdin) , freopen("output.txt" , "w" , stdout) ;
#endif
    Time
}

int main() {
    ABDEL3AL() ;
    int n ; cin >> n ;
    string s , ans ;
    cin >> s ;
    vector < string > v ;
    for (int i = 0; i < sz(s); i++) {
        if (s[i] == 'x') ans += 'x' ;
        else {
            v.pb(ans) ;
            ans = "" ;
        }
    }
    int sum = 0 ;
    for (int i = 0; i < sz(v); i++) {
        while (sz(ans) != 2) ans.pop_back() , sum += 1 ;
    }
    cout << sum << "\n" ;
    return 0;
}