#include <iostream>
#include <string>

using namespace std;
int main()
{
	int a=0, b=0, c=0, d=0;
	string str;
	cin >> str;
	for (int i = 0; i < str.length(); i++)
	{
		if (str[i] == 't') a++;
		
		if (str[i] == 'r') b++;

		if (str[i] == 'e') c++;

		if (a >= 1 && b >= 1 && c >= 2)
		{
			d++;
			a--; 
			b--;
			c -= 2;
		}
	}

	cout << d << endl;
	return 0;
}