Bob, Jim, and Mimi are sitting in the park and talking about the great birthday party Bob had recently. Suddenly, Bob asks: "Mimi, when is your birthday?" Mimi replies: "Let's see if you can figure it out". Mimi takes out a sheet of paper and writes the following dates on it: April 20 June 19 April 21 June 21 April 24 July 19 May 22 July 20 May 23 July 22 Then, she says: "One of these dates is my birthday. I will now tell Bob the month of my birthday, and I will tell Jim the day of my birthday". So, Mimi whispers the month in Bob's ear, and she whispers the day in Jim's ear. Mimi says: "without saying out loud what I just whispered in your ears, do any of you know my birthday?" Bob says: "I don't know, and I know that Jim doesn't know either" Jim says: "At first I didn't know, but now I know". Bob says: "Now I know too". What is Mimi's birthday?

Mimi takes out a sheet of paper and writes the following dates on it: April 20 June 19 April 21 June 21 April 24 July 19 May 22 July 20 May 23 July 22