#include <bits/stdc++.h>

using namespace std;

typedef unsigned long long ull;
typedef long long ll;

int main(){
	string s;
	cin >> s;
	vector<int> cnt(26, 0);
	for(int i=0; i<s.length(); i++) cnt[s[i]-'a']++;
	cout << min({cnt['t'-'a'], cnt['r'-'a'], cnt['e'-'a']/2}) << endl;
	return 0;
}