#include <bits/stdc++.h>

using namespace std;

int main() {
    string s;
    cin >> s;

    map<char, int> mp;
    for (char i : s) {
        mp[i]++;
    }

    int ans = min({mp['t'], mp['r'], mp['e'] / 2});
    cout << ans << endl;
    return 0;
}