#include<stdio.h>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <algorithm>
#include <sstream>
#include <iostream>
#include <string>
#include <stdio.h>

using namespace std;

int main() {

	string S;
	cin >> S;

	int cnt = 0, c[3] = {};
	for (int i = 0; i < S.size(); i++) {
		if (S[i] == 't') c[0]++;
		if (S[i] == 'r') c[1]++;
		if (S[i] == 'e') c[2]++;
	}

	c[2] /= 2;

	cnt = min(c[0], min(c[1], c[2]));

	cout << cnt << endl;

	return 0;
}