#include <iostream>
#include <string>
#include <array>
int main() {
	std::string str;
	std::cin >> str;
	std::array<int, 3> count{ 0, 0, 0 };
	for (const auto &c : str) {
		switch (c) {
		case 't':
			++count[0];
			break;
		case 'r':
			++count[1];
			break;
		case 'e':
			++count[2];
		}
	}
	int min = str.size();
	count[2] >>= 1;
	for (const auto &c : count) {
		if (min > c) {
			min = c;
		}
	}
	std::cout << min << std::endl;
	return 0;
}