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

int main(void){
	string s;
	cin >> s;
	map<char,int> mp;
	for(int i=0;i<s.size();i++){
		mp[s[i]]++;
	}
	int ret = 1e6;
	ret = min(ret,mp['t']);
	ret = min(ret,mp['r']);
	ret = min(ret,mp['e']/2);
	cout << ret << endl;
	return 0;
}