#include <bits/stdc++.h>
#define rep(i, a) rep2 (i, 0, a)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) repr2 (i, 0, a)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
#define chmin(a, b) ((b) < a && (a = (b), true))
#define chmax(a, b) (a < (b) && (a = (b), true))
#define rng(a) (a).begin(), (a).end()
using namespace std;
typedef long long ll;

int main() {
	vector<int> num(26);
	string s;
	cin >> s;
	rep (i, s.length()) {
		num[s[i] - 'a']++;
	}
	int ans = min({num['t' - 'a'], num['r' - 'a'], num['e' - 'a'] / 2});
	cout << ans << endl;
}