#include <iostream>
#include <algorithm>
#include <map>

void solve() {
    std::string s;
    std::cin >> s;

    std::map<char, int> cnt;
    for (char c : s) {
        if (!cnt.count(c)) cnt[c] = 0;
        ++cnt[c];
    }

    std::cout << std::min({cnt['t'], cnt['r'], cnt['e'] / 2})
              << std::endl;
}

int main() {
    std::cin.tie(nullptr);
    std::cout.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}