let _D = "1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991"
let ord0 = int_of_char '0'

let mult_num opr =
  let rec mult_num' idx carry result =
    if idx < 0 && carry = 0 then result
    else
      let dig_num = if idx < 0 then 0 else (int_of_char _D.[idx]) - ord0 in
      let dig_mult = dig_num * opr + carry in
      let nextCarry = dig_mult / 10
      and nextResult = (string_of_int (dig_mult mod 10)) :: result
    in
    mult_num' (idx - 1) nextCarry nextResult
  in
  let result = mult_num' 189  0 [] in
  List.fold_left (fun str c -> str ^ c) "" result

let formatNum num =
  let slen = String.length num in
  if slen <= 190 then "0." ^ num
  else (String.sub num 0 (slen - 190))
     ^ "."
     ^ (String.sub num (slen - 190) 190)
     
let () =
  let _N = read_int () in
  mult_num _N |>
  formatNum |>
  print_endline