#include <bits/stdc++.h>

using namespace std;

#define REP(i, n) for(int i = 0; i < n; i++)

int main() {
    string s;
    cin >> s;

    int cntT = 0, cntR = 0, cntE = 0;
    REP(i, s.length()) {
        switch (s[i]) {
            case 't':
                cntT++;
                break;
            case 'r':
                cntR++;
                break;
            case 'e':
                cntE++;
                break;
        }
    }

    cout << min({cntT, cntR, cntE / 2}) << endl;
    return 0;
}