#include <algorithm>
#include <iostream>
#include <string>
#include <cmath>


using namespace std;

int main() {

	string s;
	cin >> s;

	int t=0,r=0,e=0;

	for(int i=0; i<s.length();i++){
		if(s[i] == 't'){
			t++;
		}
		if(s[i] == 'r'){
			r++;
		}
		if(s[i] == 'e'){
			e++;
		}
	}

/*
	cout<<"t"<<t<<endl;
	cout<<"r"<<r<<endl;
	cout<<"e"<<e<<endl;
*/

	int  min1 = min(t,r);

	int ans = min(min1,e/2);

	cout<<ans<<endl;

	return 0;
}