If you have the opportunity to say Dec 31, you win. If you have the opportunity to say Nov 30, you win. That's because: I can then only say Dec 30. You then say Dec 31 and win. If you have the opportunity to say Oct 29, you win. That's because: If I then say Oct 30, you then say Nov 30 and win. If I then say Oct 31, you will say Dec 31 and win. If I then say Nov 29, you will say Nov 30 and win. If I then say Dec 29, you will say Dec 31 and win. If you have the opportunity to say Sep 28, you win. That's because: If I then say Sep 29, you will say Oct 29 and win. If I then say Sep 30, you will say Nov 30 and win. If I then say Oct 28, you will say Oct 29 and win. If I then say Nov 28, you will say Nov 30 and win. If I then say Dec 28, you will say Dec 31 and win. If you have the opportunity to say Aug 27, you win. That's because: If I then say Aug 28, you will say Sep 28 and win. If I then say Aug 29, you will say Oct 29 and win. If I then say Aug 30, you will say Nov 30 and win. If I then say Aug 31, you will say Dec 31 and win. If I then say Sep 27, you will say Sep 28 and win. If I then say Oct 27, you will say Oct 29 and win. If I then say Nov 27, you will say Nov 30 and win. If I then say Dec 27, you will say Dec 31 and win. If you have the opportunity to say Jul 26, you win. That's because: If I then say Jul 27, you will say Aug 27 and win. If I then say Jul 28, you will say Sep 28 and win. If I then say Jul 29, you will say Oct 29 and win. If I then say Jul 30, you will say Nov 30 and win. If I then say Jul 31, you will say Dec 31 and win. If I then say Aug 26, you will say Sep 28 and win. If I then say Sep 26, you will say Sep 28 and win. If I then say Oct 26, you will say Oct 29 and win. If I then say Nov 26, you will say Nov 30 and win. If I then say Dec 26, you will say Dec 31 and win. If you have the opportunity to say Jun 25, you win. That's because: If I then say Jun 26, you will say Jul 26 and win. If I then say Jun 27, you will say Aug 27 and win. If I then say Jun 28, you will say Sep 28 and win. If I then say Jun 29, you will say Oct 29 and win. If I then say Jun 30, you will say Nov 30 and win. If I then say Jul 25, you will say Jun 26 and win. If I then say Aug 25, you will say Aug 27 and win. If I then say Sep 25, you will say Sep 28 and win. If I then say Oct 25, you will say Oct 29 and win. If I then say Nov 25, you will say Nov 30 and win. If I then say Dec 25, you will say Dec 31 and win. If you have the opportunity to say May 24, you win. That's because: If I then say May 25. you will say Jun 25 and win. If I then say May 26, you will say Jul 26 and win. If I then say May 27, you will say Aug 27 and win. If I then say May 28, you will say Sep 28 and win. If I then say May 29, you will say Oct 29 and win. If I then say May 30, you will say Nov 30 and win. If I then say May 31, you will say Dec 31 and win. If I then say Jun 24, you will say Jun 25 and win. If I then say Jul 24, you will say Jul 26 and win. If I then say Sep 24, you will say Sep 28 and win. If I then say Oct 24, you will say Oct 29 and win. If I then say Nov 24, you will say Nov 30 and win. If I then say Dec 24, you will say Dec 31 and win. If you have the opportunity to say Apr 23, you win. That's because: If I then say Apr 24, you will say May 24 and win. If I then say Apr 25, you will say Jun 25 and win. If I then say Apr 26, you will say Jul 26 and win. If I then say Apr 27, you will say Aug 27 and win. If I then say Apr 28, you will say Sep 28 and win. If I then say Apr 29, you will say Oct 29 and win. If I then say Apr 30, you will say Nov 30 and win. If I then say May 23, you will say May 24 and win. If I then say Jun 23, you will say Jun 25 and win. If I then say Jul 23, you will say Jun 26 and win. If I then say Aug 23, you will say Aug 27 and win. If I then say Sep 23, you will say Sep 28 and win. If I then say Oct 23, you will say Oct 29 and win. If I then say Nov 23, you will say Nov 30 and win. If I then say Dec 23, you will say Dec 31 and win. If you have the opportunity to say Mar 22, you win. That's because: If I then say Mar 23, you will say Apr 23 and win. If I then say Mar 24, you will say May 24 and win. If I then say Mar 25, you will say Jun 25 and win. If I then say Mar 26, you will say Jul 26 and win. If I then say Mar 27, you will say Aug 27 and win. If I then say Mar 28, you will say Sep 28 and win. If I then say Mar 29, you will say Oct 29 and win. If I then say Mar 30, you will say Nov 30 and win. If I then say Mar 31, you will say Dec 31 and win. If I then say Apr 22, you will say Apr 23 and win. If I then say May 22, you will say May 24 and win. If I then say Jun 22, you will say Jun 25 and win. If I then say Jul 22, you will say Jun 26 and win. If I then say Aug 22, you will say Aug 27 and win. If I then say Sep 22, you will say Sep 28 and win. If I then say Oct 22, you will say Oct 29 and win. If I then say Nov 22, you will say Nov 30 and win. If I then say Dec 22, you will say Dec 31 and win. If you have the opportunity to say Feb 21, you win. That's because: If I then say Feb 22, you will say Mar 22 and win. If I then say Feb 23, you will say Apr 23 and win. If I then say Feb 24, you will say May 24 and win. If I then say Feb 25, you will say Jun 25 and win. If I then say Feb 26, you will say Jul 26 and win. If I then say Feb 27, you will say Aug 27 and win. If I then say Feb 28, you will say Sep 28 and win. If I then say Feb 29 (leap year), you will say Oct 29 and win. If I then say Mar 21, you will say Mar 22 and win. If I then say Apr 21, you will say Apr 23 and win. If I then say May 21, you will say May 24 and win. If I then say Jun 21, you will say Jun 25 and win. If I then say Jul 21, you will say Jul 26 and win. If I then say Aug 21, you will say Aug 27 and win. If I then say Sep 21, you will say Sep 28 and win. If I then say Oct 21, you will say Oct 29 and win. If I then say Nov 21, you will say Nov 30 and win. If I then say Dec 21, you will say Dec 31 and win. If you have the opportunity to say Jan 20, you win. That's because: If I then say Jan 21, you will say Feb 21 and win. If I then say Jan 22, you will say Mar 22 and win. If I then say Jan 23, you will say Apr 23 and win. If I then say Jan 24, you will say May 24 and win. If I then say Jan 25, you will say Jun 25 and win. If I then say Jan 26, you will say Jul 26 and win. If I then say Jan 27, you will say Aug 27 and win. If I then say Jan 28, you will say Sep 28 and win. If I then say Jan 29, you will say Oct 29 and win. If I then say Jan 30, you will say Nov 30 and win. If I then say Jan 31, you will say Dec 31 and win. If I then say Feb 20, you will say Feb 21 and win. If I then say Mar 20, you will say Mar 22 and win. If I then say Apr 20, you will say Apr 23 and win. If I then say May 20, you will say May 24 and win. If I then say Jun 20, you will say Jun 25 and win. If I then say Jul 20, you will say Jul 26 and win. If I then say Aug 20, you will say Aug 27 and win. If I then say Sep 20, you will say Sep 28 and win. If I then say Oct 20, you will say Oct 29 and win. If I then say Nov 20, you will say Nov 30 and win. If I then say Dec 20, you will say Dec 31 and win. Answer: January 20. Edwin