#include"bits/stdc++.h"
using namespace std;
int main() {
	int t, r, e; string s;
	t = 0; r = 0; e = 0;
	cin >> s;
	for (int i = 0; i < s.length(); i++) {
		if (s[i] == 't')t++;
		if (s[i] == 'r')r++;
		if (s[i] == 'e')e++;
	}
	t = min(t, r); t = min(t, e / 2);
	cout << t << endl;
}