#include"bits/stdc++.h"
using namespace std;


int main() {
	string s;
	cin >> s;
	map<char,int> m;
	for (int i = 0; i < s.length(); i++) {
		m[s[i]]++;
	}
	int t,r,e;
	t=r=e=0;

	for (auto itr = m.begin(); itr != m.end(); itr++) {
		if(itr->first == 't') t=itr->second;
		if(itr->first == 'r') r=itr->second;
		if(itr->first == 'e') e=itr->second;
	}

	e /= 2;
	int ans = min(t,min(r,e));

	cout << ans << endl;
}