#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

int main(){
	string s;
	cin >> s;
	int n = s.size();
	vector<int> cnt(26, 0);
	for(int i=0; i<n; i++){
		cnt[s[i]-'a']++;
	}

	int ans = min({cnt['t'-'a'], cnt['r' - 'a'], cnt['e' - 'a']/2});
	cout << ans << endl;
	return 0;
}