#include <iostream>
#include <string>
#include <vector>
#include <cstring>
#include <climits>
#include <algorithm>
#include <map>
using namespace std;

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