#include <iostream>
#include <algorithm>
using namespace std;
 
int main(){
	string S;
	cin >> S;
	int t = 0, r = 0, e = 0;
	for(int i = 0; i < S.size(); i++){
		if(S[i] == 't'){
			t++;
		}else if(S[i] == 'r'){
			r++;
		}else if(S[i] == 'e'){
			e++;
		}
	}
	cout << min({t, r, e / 2}) << endl;
}