#include <iostream>
#include <algorithm>
#include <vector>
#include <deque>
#include <string>
#include <tuple>
#include <functional>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <map>
#include <random>
//#include "toollib.h"
#define INT_MAX 2147483647
#define Loop(i, n) for(int i = 0; i < (int)n; i++)
#pragma warning (disable:4018)

using namespace std;
typedef long long int lint;

//***** Main Program *****

int main() {
	string S;
	cin >> S;
	int count_t = 0, count_r = 0, count_e = 0;
	Loop(i, S.length()) {
		if (S[i] == 't') count_t++;
		else if (S[i] == 'r') count_r++;
		else if (S[i] == 'e') count_e++;
	}
	int ret = min({ count_t, count_r, count_e / 2 });
	cout << ret << endl;
	return 0;
}