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

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

	int t, r, e;
	t = 0;
	r = 0;
	e = 0;
	for (int i = 0; i < s.size(); i++) {
		char c = s.at(i);
		if (c == 't') t++;
		if (c == 'r') r++;
		if (c == 'e') e++;
	}

	e /= 2;
	int a = min(t, min(r, e));

	cout << a << endl;
}