#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <stack>
#include <algorithm>
#include <string>
#include <map>
#include <iterator>
#include <set>
#include <queue>

using namespace std;


int main() {

    string s;
    cin >> s;
    // 0 => t
    // 1 -> r
    // 2 -> e
    vector<int> v(3, 0);

    for (int i = 0; i < s.size(); ++i) {
        if (s[i] == 't') {
            v[0] += 1;
        } else if (s[i] == 'r') {
            v[1] += 1;
        } else if (s[i] == 'e') {
            v[2] += 1;
        }
    }

    int cnt = 0;
    while (v[0] > 0 and v[1] > 0 and v[2] > 1) {

        v[0] -= 1;
        v[1] -= 1;
        v[2] -= 2;
        cnt += 1;
    }

    cout << cnt << endl;

    return 0;
}