#include <bits/stdc++.h>
using namespace std;

int main(){
	ios::sync_with_stdio(false);
	cin.tie(0);  
	string s;
	cin >> s;
	int t = 0, r = 0, e = 0;
	for(int i = 0; i < s.size(); i++) {
		if(s[i] == 't') t++;
		if(s[i] == 'r') r++;
		if(s[i] == 'e') e++;
	}
	cout << min(min(t, r), e / 2) << endl;
	return 0;	
}