let
  s = readLine stdin

var
  cnts = (t: 0, r: 0, e: 0)

for c in s:
  case c
  of 't': inc cnts.t
  of 'r': inc cnts.r
  of 'e': inc cnts.e
  else: discard

echo min [cnts.t, cnts.r, cnts.e div 2]