Problems

# Tale about an apple

# Tale about an apple

Once the king gave the farmer an apple from his garden. Farmer went to the garden and sees: the entire garden is surrounded with **n** fences, each fence has only one gate, and at each gate stands a guard. The farmer came to the first guard and showed him the royal decree, and guard said to him: "*Go and take, but when you return, give me half of your apples plus one*". The same was said by the second, third guard, etc. How many apples must take the farmer to pay all the guards and leave only one apple for himself?

#### Input

The only number **n** – the number of fences in the garden (**1** ≤ **n** ≤ **62**).

#### Output

The number of apples, which should take the farmer to pay off all the guards a leave one apple for himself.

Input example #1

1

Output example #1

4

Input example #2

2

Output example #2

10