open Scanf
open Printf

let id a = a
let pair a b = a, b
let triplet a b c = a, b, c

let rec scan_list = function
  | 1 -> scanf "%d" (fun k -> [k])
  | n -> scanf "%d " (fun k -> k :: scan_list (n-1))

let f a b = if a + b = 15
  then printf "+\n"
  else if a * b = 15
  then printf "*\n"
  else printf "x\n"

let () = scanf "%d %d\n" f