#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
#define co(x) cout << (x) << "\n"
#define cosp(x) cout << (x) << " "
#define ce(x) cerr << (x) << "\n"
#define cesp(x) cerr << (x) << " "
#define pb push_back
#define mp make_pair
#define Would
#define you
#define please

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);


	string S;
	cin >> S;

	int C[300] = {};
	rep(i, S.size()) {
		C[S[i]]++;
	}

	int saishou = 1e9;
	saishou = min(saishou, C['t']);
	saishou = min(saishou, C['r']);
	saishou = min(saishou, C['e'] / 2);

	co(saishou);


	Would you please return 0;
}