#include <iostream>
#include <algorithm>
#include <map>

#include <vector>

using namespace std;

int main() {
	
	string s;
	cin >> s;
	vector<int> v(100,0);
	for(char it:s) {
		v[it] += 1;
	}
	v['e'] /= 2;
	cout << min({v['t'],v['r'],v['e']});
	
}