#include <iostream>
using namespace std;

string S;

void Solve() {
    int t_count = 0, r_count = 0, e_count = 0;
    for (int i = 0; i < S.size(); i++) {
        if (S[i] == 't') t_count++;
        else if (S[i] == 'r') r_count++;
        else if (S[i] == 'e') e_count++;
    }
    cout << min(t_count, min(r_count, e_count / 2)) << endl;
}

int main() {
    cin >> S;

    Solve();

    return 0;
}