#include <bits/stdc++.h>
using namespace std;

int main() {
    string s;
    cin >> s;
    int t = 0, r = 0, e = 0;
    for (char c : s) {
        switch (c) {
            case 't':
            t++;
            break;
            case 'r':
            r++;
            break;
            case 'e':
            e++;
            break;
        }
    }
    cout << min({t, r, e / 2}) << endl;
}