Rohan is on his way to visit his girlfriend, who lives at the end of the state.It's her birthday, and he want to give her the cakes that he has made.Between his place and her girlfriend's house, he need to cross 7 toll bridges.

Before you can cross the toll bridge, you need to give them half of the cakes you are carrying, but as they are kind trolls, they each give you back a single cake.

How many cakes do Rohan have to carry with him so he can reach his girlfriend's home with exactly 2 cakes?