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 ≤ 10^6). The second line contains 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.

Examples