#include "bits/stdc++.h"

using namespace std;
using ll = long long;
const double pi = acos(-1);
#define FOR(i,a,b) for (ll i=(a),__last_##i=(b);i<__last_##i;i++)
#define RFOR(i,a,b) for (ll i=(b)-1,__last_##i=(a);i>=__last_##i;i--)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define __GET_MACRO3(_1, _2, _3, NAME, ...) NAME
#define rep(...) __GET_MACRO3(__VA_ARGS__, FOR, REP)(__VA_ARGS__)
#define rrep(...) __GET_MACRO3(__VA_ARGS__, RFOR, RREP)(__VA_ARGS__)
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v) {
	REP(i, v.size()) { if (i)os << " "; os << v[i]; }return os;
}
template<typename T> ostream& operator<<(ostream& os, const vector<vector<T>>& v) {
	REP(i, v.size()) { if (i)os << endl; os << v[i]; }return os;
}

const ll INF = 1LL << 60;
ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	string s;
	vector<ll> v(3, 0);
	ll ans = 0;

	cin >> s;

	REP(i, s.size()) {
		if (s[i] == 't') {
			v[0]++;
		}
		else if (s[i] == 'r') {
			v[1]++;
		}
		else if (s[i] == 'e') {
			v[2]++;
		}
	}

	while (v[0] > 0) {
		if (v[1] < 1 || v[2] < 2) {
			break;
		}
		ans++;
		v[0]--;
		v[1]--;
		v[2] -= 2;
	}

	cout << ans << endl;
}