#include <bits/stdc++.h>

[[nodiscard]] static inline constexpr std::array<int_fast32_t, 128> prepare(const std::string& S) noexcept
{
	std::array<int_fast32_t, 128> count_of = { 0, };
	for (const auto& s : S)
		++count_of[s];

	return count_of;
}

[[nodiscard]] static inline constexpr int_fast32_t solve(const std::array<int_fast32_t, 128>& count_of) noexcept
{
	return std::min<int_fast32_t>({ count_of['t'], count_of['r'], count_of['e'] / 2 });
}

int main()
{
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	
	std::string S;
	S.reserve(1'000'000), std::cin >> S;

	std::cout << solve(prepare(S)) << '\n';
	return 0;
}