#include<iostream>
#include<string>
int main()
{
	std::string s;

	std::cin >> s;
	int t = 0, r = 0, e = 0;
	for (const char c : s)
	{
		if (c == 't')
		{
			t++;
		}
		else if (c == 'r')
		{
			r++;
		}
		else if (c == 'e')
		{
			e++;
		}
	}

	e /= 2;

	if (t <= r && t <= e)
	{
		std::cout << t << std::endl;
	}
	else if (r <= t && r <= e)
	{
		std::cout << r << std::endl;
	}
	else if (e <= t && e <= r)
	{
		std::cout << e << std::endl;
	}
}