A trolling questionDiscrete Mathematics Level 2
You're walking through an old bridge when the bridge suddenly breaks and you fall in the valley below. As you crash into the rocks, you realise that somehow, you survived the fall. But suddenly, an evil troll appears out of nowhere. Behind him there are three portals that had entrances covered by a really cloudy mist you can't see through. The troll laughs an evil laugh and says " I have three portals here: one will lead you at the top of the valley, and two will trap you in hell. Choose your portal now." You choose the first one. "Well," says the troll," How about now?" Another portal disappears but you don't know where that portal will lead you. So, which portal should you stick with your portal or switch to the other one to have te highest chance to go back to the top of the valley?