Competitions

# Set + Multiset

# Sweets for mushrooms

It seems strange, but mushrooms like soda. Moreover, Michael likes to make experiments with it. Each kind of soda has it's own level of sweetness. Michael has **n** containers with soda of different levels. If Michael mix two containers with levels **x** and **y**, instead of these two he will get soda with level **2** * min(**x**,**y**).

Help Michael to get soda with the highest possible level of sweetness.

#### Input

The first line contains the number of containers **n** (**1** ≤ **n** ≤ `10`

). The second line contains ^{6}**n** integers: the level of sweetness `x`

(_{i}`-10`

≤ ^{9}`x`

≤ _{i}`10`

).^{9}

#### Output

Print the highest possible level of sweetness that can be obtained by mixing some of the available sodas.

Input example #1

3 1 3 6

Output example #1

6

Input example #16

4 5 8 10 19

Output example #16

38