#include <bits/stdc++.h>
using namespace std;
int main(){
  string S;
  cin >> S;
  int N = S.size();
  int t = 0;
  int r = 0;
  int e = 0;
  for (int i = 0; i < N; i++){
    if (S[i] == 't'){
      t++;
    }
    if (S[i] == 'r'){
      r++;
    }
    if (S[i] == 'e'){
      e++;
    }
  }
  cout << min({t, r, e / 2}) << endl;
}