#include "bits/stdc++.h"
using namespace std;

int main() {
	int T = 0, R = 0, E = 0;
	string S;
	cin >> S;
	for (int i = 0; i < S.size(); i++) {
		if (S[i] == 't') T++;
		if (S[i] == 'r') R++;
		if (S[i] == 'e') E++;
	}
	cout << min(min(T, R), E / 2) << endl;
}