#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[i] == 't') t++;
    else if (s[i] == 'r') r++;
    else if (s[i] == 'e') e++; 
  }
  cout << min({t, r, e/2}) << endl;
  return 0;
}