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

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