#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
using namespace std;

int main()
{
	string s;
	cin >> s;
	int t=0, r=0, e=0;
	for (int i = 0; i < s.size(); i++){
		if (s[i] == 't')t++;
		else if (s[i] == 'r') r++;
		else if (s[i] == 'e') e++;
	}
	int n;
	n = min(t, r);
	n = min(n, e / 2);

	cout << n << endl;

	return 0;
}