#include <bits/stdc++.h>
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.at(i) == 't') t++;
    if (S.at(i) == 'r') r++;
    if (S.at(i) == 'e') e++;
  }
  cout << min({t, r, e / 2}) << "\n";
}