#include <bits/stdc++.h>
using namespace std;
int a[26];

int main() {
  string s;
  cin >> s;
  for (auto& c : s) {
    a[c - 'a']++;
  }
  int b[] = {a['t' - 'a'], a['r' - 'a'], a['e' - 'a'] / 2};
  sort(b, b + 3);
  cout << b[0] << endl;
  return 0;
}