#include<bits/stdc++.h>
#define rep(i, x) for(ll i = 0; i < x; i++)
#define rep2(i, x) for(ll i = 1; i <= x; i++)
#define all(a) (a).begin(),(a).end()
using ll = long long;
using ld = long double;
const ll INF = 10000000000000000;
using namespace std;
signed main() {
	string s; cin >> s; ll n = s.size(), t = 0, r = 0, e = 0;
	rep(i, n) {
		if (s[i] == 't') { t++; } if (s[i] == 'r') { r++; } if (s[i] == 'e') { e++; }
	}
	cout << min({ t,r,e / 2 }) << endl;
	return 0;
}