#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
using namespace std;
using ll = long long;

int f(string const& s, char c) {
    return count(s.begin(), s.end(), c);
}

int main() {
    string s;
    cin >> s;
    cout << min(f(s, 't'), min(f(s, 'r'), f(s, 'e')/2)) << endl;
}