def round_check(question):

    while True:
        error = "Please enter an integer that is between 5 and 15."

        to_check = input(question)

        # check for infinite mode
        if to_check == "":
             return "infinite"
        elif to_check == "xxx":
            return "xxx"
        try:
            response = int(to_check)

            # check that the number is more than / equal to 1
            if response < 5:
                print()
                print(error)
                print()
            elif response > 15:
                print()
                print(error)
                print()

            else:
               return response

        except ValueError:
            print()
            print(error)
            print()

round_check("How many rounds? ")