#include<iostream>
#include<string>
#include<cstring>
#include<cstdio>
#include<stack>

using namespace std;
const int N = 2e5+10;

int main(){

 /*freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);*/
    char str[N];
    char ans[N];
    int n;
    cin>>n>>str;
    int res = 0;
    for(int i = 0,j = 0;i<n;++i){
        ans[j++]=str[i];
        if(ans[j-1]=='x'&&j>=3){if(ans[j-2]=='o'&&ans[j-3]=='f')j-=3,res+=3;}
    }
    cout<<n-res<<endl;
  /* fclose(stdin);
    fclose(stdout);*/
}
#include <iostream>
#include <cmath>
#include <iomanip>
#include <vector>
#include <stack>
#include <queue>
#include <list>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <iterator>
#include <unordered_map>
#include <unordered_set>
#include <sstream>
#include <fstream>
#include <numeric>
#include <tuple>
#include <ctime>
#include <random>

using namespace std;

#define fori(t) for(int i = 0; i < t; ++i)
#define forj(n) for(int j = 0; j < n; ++j)
#define fork(n) for(int k = 0; k < n; ++k)
#define forai(a) for(auto& i : a)
#define foraj(a) for(auto& j : a)
#define forak(a) for(auto& k : a)
#define forp(s, n, d) for(int p = s; p < n; p += d)
#define fast cin.tie(0); cout.tie(0); std::ios_base::sync_with_stdio(0);
#define pb(a) push_back(a);
#define pob(a) pop_back(a);
#define sorti(a) sort((a).begin(), (a).end());
#define sortm(a, n) sort(a, a + n);
#define reversi(a) reverse((a).begin(), (a).end());
#define all(a) (a).begin(), (a).end()
#define fi first
#define se second
#define yes cout << "Yes\n";
#define no cout << "No\n";
#define ans(a) cout << a << '\n';
#define endl cout << '\n';
#define res(a, n) (a).resize(n);
#define read(a, n) (a).resize(n); fori(n) cin >> a[i];
#define print(a) for (auto i : a) cout << i << ' ';
#define clear(a) (a).clear();
//#define int long long
//#define double long double

typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> ii;
typedef pair<long long, long long> llll;
typedef vector<int> vi;
typedef vector<long long> vll;
typedef vector<pair<int, int>> vii;
typedef vector<pair<int, pair<int, int>>> viii;
typedef pair<int, pair<int, int>> iii;
typedef vector<pair<long long, long long>> vllll;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
typedef vector<bool> vb;
typedef pair<char, char> cc;
typedef pair<pair<char, char>, char> ccc;
typedef vector<char> vc;
typedef pair<int, char> ic;
typedef pair<ii, char> iic;
typedef vector<bool> vb;
typedef set<int> si;
typedef vector<vector<ii>> vvii;
typedef vector<vector<iii>> vviii;
typedef vector<vector<llll>> vvllll;

const int INF = 2147483647;
const ll LONGINF = 9223372036854775807;
const ll MOD = 1e9 + 7;

string s;
list<char> help;

void solve()
{
    int n;
    cin >> n >> s;
    string est = "";
    fori(n) help.push_back(s[i]);
    auto i = help.begin();
    while (i != help.end())
    {
        est += *i;
        if (est.size() == 3)
        {
            if (est == "fox")
            {
                auto first = i, last = i;
                --first;
                --first;
                ++last;
                auto next = help.erase(first, last);
                if (next != help.begin()) --next;
                if (next != help.begin()) --next;
                i = next;
                est = "";
            }
            else
            {
                string temp = est;
                est = "";
                est += temp[1];
                est += temp[2];
                ++i;
            }
        }
        else ++i;
    }
    ans(help.size())
}

signed main()
{
    fast
    bool mult = false;
    if (mult)
    {
        int t;
        cin >> t;
        while (t--) solve();
    }
    else solve();
    return 0;
}
