#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
#include<iomanip>
using namespace std;
typedef long long int lont;
int main() {
	string S;
	cin >> S;
	int Z = S.size();
	int t, r, e;
	t = 0;
	r = 0;
	e = 0;
	for (int ia = 0; ia < Z; ia++) {
		if (S.at(ia) == 't') {
			t+=2;
		}
		if (S.at(ia) == 'r') {
			r+=2;
		}
		if (S.at(ia) == 'e') {
			e++;
		}
	}
	int A = min(t, r);
	int B = min(A, e);
	cout << B / 2 << endl;
}