#include <bits/stdc++.h>
using namespace std;

void DBG() { cerr << endl; }
template<class Head, class... Tail>
void DBG(Head H, Tail... T) { cerr << ' ' << H; DBG(T...); }
#define dbg(...) cerr << "(" << (#__VA_ARGS__) << "):", DBG(__VA_ARGS__)

using ll = long long;
using ld = long double;

#define sqr(a) ll(a) * (a)
#define siz(a) int(a.size())
#define ints(a...) int a; read(a)
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define trav(i, v) for (const auto i : v)
#define Fill(a, b) memset(a, b, sizeof(a))
#define rep(i, b, n) for (auto i = b; i < n; i++)
#define per(i, b, n) for (auto i = b; i >= n; i--)
#define unify(a) sort(all(a)), a.resize(unique(all(a)) - a.begin())

template <class T> using vec = vector<T>;
template <class... Args> inline void read(Args&... args) { ((cin >> args), ...); }
template <class... Args> inline void show(Args... args) { ((cout << args << " "), ...); }
template <class T1, class T2> inline bool ckmin(T1 &a, T2 b) { return a > b ? a = b, 1 : 0; }
template <class T1, class T2> inline bool ckmax(T1 &a, T2 b) { return a < b ? a = b, 1 : 0;  }
template <class T> inline void operator>> (istream& in, vector<T>& v) { rep(i, 0, siz(v)) in >> v[i]; }
template <class T> inline void operator<< (ostream& out, const vector<T>& v) { rep(i, 0, siz(v)) out << v[i] << " \n"[i + 1 == siz(v)]; }

const int MOD = 1e9 + 7;

void solve() {
    ints(n);
    string s; read(s);
    auto idx = s.find("fox");
    while (idx != string::npos) {
        s.erase(idx, 3);
        idx = s.find("fox", max<int>(idx - 2, 0));
    }
    cout << siz(s);
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(12);
    cerr << fixed << setprecision(12);
    int _ = 1;
    // cin >> _;
    rep(i, 1, _ + 1) {
        // printf("Case %d: ", i);
        // Solution solve;
        solve();
    }
    return 0;
}
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
#define int ll
typedef long double ld;

typedef pair<int,int> pii;
#define x first
#define y second

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    int n;
    string s;
    cin>>n>>s;
    string t;
    for(char c:s)
    {
        t+=c;
        while(t.size()>=3&&t.substr(t.size()-3)=="fox")
            t.pop_back(),
            t.pop_back(),
            t.pop_back();
    }
    cout<<t.size();
}
