took me some time

12/31/1390 it can't be after the 1300's because the highest date in a month is 31 (inverted to 13xx for the year). the highest xx is 90 to make the month 09. the only choices are 10 20 30 40 50 60 70 80 90 01 11 and 21 for the xx anyway since there are 12 months.

i mean 09/31/1390