#include<bits/stdc++.h>
using namespace std;

int main()
{
  string S;
  cin >> S;

  int t = count(S.begin(), S.end(), 't');
  int r = count(S.begin(), S.end(), 'r');
  int e = count(S.begin(), S.end(), 'e') / 2;
  cout << min(t, min(r, e)) << endl;
}