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

int main(){
	string s;
	cin >> s;
	int t = 0;
	int r = 0;
	int e = 0;
	for(int i = 0; i < s.length(); i++){
		if(s[i] == 't')t++;
		else if(s[i] == 'r')r++;
		else if(s[i] == 'e')e++;
	}
	int ans = min(t, min(r, e / 2));
	cout << ans << endl;
}