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

signed main(){
  string S; cin >> S;
  vector< int > cnt( 256 );
  for( int i = 0; i < S.size(); ++i )
    ++cnt[ S[ i ] ];
  cout << min( { cnt[ 't' ], cnt[ 'r' ], cnt[ 'e' ] / 2 } ) << endl;
  return 0;
}