; min {(t の個数), (r の個数), (e の個数) / 2}
; を出力する
(defun main ()
  (let* ((s (read-line))
                  ; count item sequence &key from-end start end key test test-not ⇒ n 
         (t-count (count #\t s))
         (r-count (count #\r s))
         (e-count (floor (count #\e s) 2))
         (ans (min t-count r-count e-count)))
    (princ ans)
    (terpri)))
(main)