#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']++;

  int ans = 250000;
  ans = min(ans, v['t'-'a']);
  ans = min(ans, v['r'-'a']);
  ans = min(ans, v['e'-'a'] / 2);
  return ans;
}

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