#include <iostream>
#include <string>
using namespace std;

int main() {

	string s;
	int t, r, e, ans;
	cin >> s;
	t = r = e = ans = 0;

	for (size_t i = 0; i < s.size(); i++) {
		switch (s[i]) {
			case 't': t++; break;
			case 'r': r++; break;
			case 'e': e++; break;
			default: break;
		}
	}

	while (true) {
		if (t == 0 || r == 0 || e < 2) {
			break;
		}
		ans++;
		t--;
		r--;
		(--e)--;
	}
	cout << ans << endl;
	return 0;
}