#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>

using namespace std;

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

	int t = count(s.begin(), s.end(), 't');
	int r = count(s.begin(), s.end(), 'r');
	int e = count(s.begin(), s.end(), 'e') / 2;

	cout << min(min(t, r), e) << endl;
	return 0;
}