Christmas Elevator Escape

You are at the top floor of this building which has been decorated for Christmas. This decoration is for the grand Christmas Party that has been organized at the ground floor. You are also invited to the party but it seems like the organizers have set up a game for you. The elevator is locked and the keys are hidden on each floor. You are expected to search each floor and find the keys to the elevator doors and get down the floors to finally reach the ground floor where the party has already started. Let us what you can do to save your Christmas celebrations.