#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <iomanip>
#include <cmath>
#include <functional>
using namespace std;
#define diff(x,y) ((x > y) ? (x - y) : (y - x))
#define us(x) (x > 0) ? x : x * -1
#define lli long long int

int main() {
	int t = 0, r = 0, e = 0, ans = 0;
	string str;
	cin >> str;
	for (int i = 0; i < str.size(); i++) {
		switch (str[i]) {
		case 't':
			t++;
			break;
		case 'r':
			r++;
			break;
		case 'e':
			e++;
			break;
		default:
			break;
		}
		if (t > 0 && r > 0 && e > 1) {
			ans++;
			t--;
			r--;
			e -= 2;
		}
	}
	cout << ans << endl;
	return 0;
}