import strutils, sequtils

let
  t = stdin.readLine.split.map parseInt
  (N, G, V) = (t[0], t[1], t[2])

  fvYn = N div 5
  mg = fvYn * G


stdout.write mg div V
stdout.write ($(mg mod V / V).formatFloat(ffDecimal, 12))[1 .. ^1]

echo()