#include <iostream>
using namespace std;
int main(void) {
	string s;
	cin >> s;
	int t = 0, r = 0, e = 0;
	for (int i = 0; i < s.size(); ++i) {
		if (s[i] == 't') ++t;
		else if (s[i] == 'r') ++r;
		else if (s[i] == 'e') ++e;
	}
	e /= 2;
	cout << min(t, min(r, e)) << endl;
	return 0;
}