#include <iostream>		//cin, cout
#include <vector>		//vector
#include <algorithm>	//sort,min,max,count
#include <string>		//string,getline, to_string
#include <cstdlib>		//abs(int)
#include <utility>		//swap, pair
#include <deque>		//deque
#include <climits>		//INT_MAX
#include <bitset>		//bitset
#include <cmath>		//sqrt, ceil. M_PI, pow, sin

using namespace std;

int main() {

	string S;
	cin >> S;

	int t = 0, r = 0, e = 0;

	for (unsigned int i = 0; i < S.length(); i++) {
		if (S [i]== 't') {
			t++;
		}
		else if (S[i] == 'r') {
			r++;
		}
		else if (S[i] == 'e') {
			e++;
		}
	}

	e = e / 2;

	int min = t;
	if (min > r) { min = r; }
	if (min > e) { min = e; }

	cout << min << endl;
	
	return 0;

}