In the forest the lake with lilies started to bloom. On the first day only one lily bloomed, and then every day the number of blooming lilies doubled. On the n-th day the whole lake was covered with blooming lilies. At what day the half of the lake surface was covered with blooming lilies?

Input

The number of days n (1 < n ≤ 200) when the entire surface of the lake was covered with blooming lilies.

Output

Print the day number when half of the lake surface was covered with blooming lilies.