#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
#include<unordered_map>
#include<unordered_set>
//#include<quadmath.h>
using namespace std;

int countt[27];
int main(){
	string s;
	cin >> s;
	for (int i = 0; i < s.size(); i++){
		countt[s[i] - 'a']++;
	}
	int mint = INT_MAX;
	mint = min(mint, countt['t' - 'a']);
	mint = min(mint, countt['r' - 'a']);
	mint = min(mint, countt['e' - 'a'] / 2);
	cout << mint << endl;
	return 0;
}