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

int main() {
	string str;
	cin >> str;
	int t=0;
	int r=0;
	int e=0;
	for(size_t i=0; i<str.length(); ++i) {
		switch (str[i]) {
			case 't': ++t; break;
			case 'r': ++r; break;
			case 'e': ++e; break;
		}
	}
	cout << min(min(t,r), e/2) << endl;
	return 0;
}