I’m planing trip around the Europe nex summer

I live in Belgrade (Serbia & Montenegro , Ex-Yugoslavia , SouthEast Europe)

My Plan is something like this …

Fly from Belgrade to Athens , buy There Interrail ticket for 3 Zones , go to Corfu , go to Rome , go to Florence , go to Venice , go to Munich , go to Strasbourg , go to Paris , go to Antwerp , go to Amstardam , go to Cologne , go to Hamburg , go to Copenhagen , go to Berlin , go to Munich Again , go to Vienna , everything with trains , and back to Belgrade by Bus.

I’ll stay in …

Athens – 1day , Corfu – 1day , Rome – 2 or 3 days , Florence – 1day, Venice – 1day , Munich – 2days , Strasbourg – 1day , Paris – 3 or 4 days , Antwerp – 1day , Amstardam – 3 or 4 days , Cologne – 1day , Hamburg – 2 or 3 days , Copenhagen – 2days , Berlin – 2days , Munich 2nd Time – 1day , Vienna – 1 or 2 days

I want to know how if anyone know , how much extra travel days will I spend in trains ?