#include <bits/stdc++.h>
#define rep(i, ss, ee) for (int i = ss; i < ee; ++i)
using namespace std;

int solve() {
  string s;
  cin >> s;
  vector<int> v(26, 0);
  rep(i, 0, s.size()) v[s[i] - 'a']++;
  return min(v['e' - 'a'] / 2, min(v['t' - 'a'], v['r' - 'a']));
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << solve() << endl;
  getchar();
}