necessary

Hey all,

Please help – this is my first ever Eurotrip! This summer, I plan to hit 5 cities in 4 countries in 14 days. Regarding transportation within Europe, here’s what I intend to do:
1) Fly out of London during afternoon to Amsterdam via easyjet.
2) Take overnight train from Amsterdam to Berlin
3) Early morning, take a day train from Berlin to Prague
4) During the evening, take overnight train from Prague to Paris.

What type of Eurail pass should I be purchasing for this journey? I am under 26 years old.