#include <iostream>
#include <string>
#include <algorithm>
#include <vector>

using namespace std;

int main() {

    std::ios::sync_with_stdio(false);
    std::cin.tie(0);

    string s;
    cin >> s;
    int t, r, e;
    t = static_cast<int>(count(s.begin(), s.end(), 't'));
    r = static_cast<int>(count(s.begin(), s.end(), 'r'));
    e = static_cast<int>(count(s.begin(), s.end(), 'e')) / 2;
    if (t > 0 && r > 0 && e > 0) {
        vector<int> vec {t, r, e};
        cout << *min_element(vec.begin(), vec.end()) << endl;
    }
    return 0;
}