#include <bits/stdc++.h>

using namespace std;

int main() {
    string s;
    cin >> s;
    int t = 0;
    int r = 0;
    int e = 0;
    for (int i = 0; i < s.size(); i++) {
        if (s.at(i) == 't') {
            t++;
        }
        if (s.at(i) == 'r') {
            r++;
        }
        if (s.at(i) == 'e') {
            e++;
        }
    }
    cout << min(t, min(r, e / 2)) << endl;
    return 0;
}