#include <bits/stdc++.h>

using namespace std;

int main()
{
	string S;
	cin >> S;
	vector<int >count(3);
	for(auto x : S)
	{
		switch(x)
		{
			case 't':
			{
				count[0]++;
				break;
			}
			case 'r':
			{
				count[1]++;
				break;
			}
			case 'e':
			{
				count[2]++;
				break;
			}
		}
	}
	count[2] /= 2;
	sort(count.begin() , count.end());
	cout << count[0] << endl;
return 0;
}