#include <algorithm>
#include <iostream>

using namespace std;

int main(int argc, const char* argv[])
{
	string S;
	cin >> S;
	int t = count(S.begin(), S.end(), 't');
	int r = count(S.begin(), S.end(), 'r');
	int e = count(S.begin(), S.end(), 'e');
	e /= 2;
	cout << min(t, min(r, e)) << endl;
	return 0;
}