#define _USE_MATH_DEFINES

#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max,count
#include <string>	//string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt
#include <sstream>	//stringstream,getline
#include <cmath>	//ceil,M_PI

using namespace std;

int main() {

	string S;
	cin >> S;

	vector<int> A(3);
	for (unsigned int i = 0; i < S.length(); i++) {
		switch (S[i]) {
		case 't': A[0]++; break;
		case 'r': A[1]++; break;
		case 'e': A[2]++; break;
		}
	}

	A[2] = A[2] / 2;
	int min = *min_element(A.begin(), A.end());

	if (min != 0) {
		cout << min << endl;
	}
	else {
		cout << 0 << endl;
	}

	return 0;

}