#include <iostream>
#include <algorithm>
using namespace std;

int main() {
  string s;
  cin >> s;
  int t = 0, r = 0, e = 0;
  for (int i = 0; i < s.size(); ++i) {
    if (s[i] == 't') t++;
    if (s[i] == 'r') r++;
    if (s[i] == 'e') e++;
  }
  int minN = min(t, min(r, e / 2));
  cout << minN << endl;
  return 0;
}