Riddle 2: Cheryl´s Birthday

Cheryl's Birthday

This time I present the famous problem recently raised at the Olympics in math Asia and Singapore from 2015 to kids in high school, which has already converted in viral on social networks, which is a sign of the interest that may raise a good conundrum in the general public. In the illustrations of this riddle I pay tribute to the great actors of an excellent movie that I recommend: "Philadelphia Story (Philadelphia Story, 1940)".

" Albert and Bernard have recently met Cheryl, and both want to find out when it's your birthday. Cheryl gives them a list of 10 possible dates:

-        May 15

-        May 16

-        May 19

-        June 17

-        June 18

       

-        July 14

-        July 16

-        August 14

-        August 15

-        August 17

Cheryl tells Albert and Bernard separate the month and day of your birthday respectively.

Albert:           I do not know when Cheryl's birthday, but I know Bernard does not know.

Bernard:       At first I knew when it was Cheryl's birthday,  but now I know.

Albert:          Then I also know when is the birthday

Cheryl.

So when is the birthday of Cheryl ?.