#include <iostream>
#include <map>
#include <algorithm>
using namespace std;

int main() {
    string S;
    cin >> S;
    map<char, int> m;
    for (int i = 0; i < S.size(); i++) {
        if (S[i] == 't' || S[i] == 'r' || S[i] == 'e') {
            if (m.find(S[i]) != m.end()) m[S[i]] += 1;
            else m[S[i]] = 1;
        }
    }
    cout << min(min(m['t'], m['r']), m['e'] / 2) << endl;
    return 0;
}