Mana Drain Flash of Insight

[emidln]

My opponent uses the flashback of Flash of Insight removing 5 cards from the game to set X = 5. I cast Mana Drain on the Flash of Insight and it resolves. On my next main phase, how much mana will Mana Drain's trigger give me?

Edit: I just searched for the answer and found it. Mods, please close this thread. Sorry.

[Clariax]

X=5.  This includes the X in the mana cost, even though you're not paying the mana cost.  So, the converted mana cost of the spell is 7.  Mana Drain will add 7 mana to your pool on your next main phase.