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