CF933C A Colourful Prospect

Firecrackers scare Nian the monster, but they're wayyyyy too noisy! Maybe fireworks make a nice complement. Little Tommy is watching a firework show. As circular shapes spread across the sky, a splendid view unfolds on the night of Lunar New Year's eve. A wonder strikes Tommy. How many regions are formed by the circles on the sky? We consider the sky as a flat plane. A region is a connected part of the plane with positive area, whose bound consists of parts of bounds of the circles and is a curve or several curves without self-intersections, and that does not contain any curve other than its boundaries. Note that exactly one of the regions extends infinitely.

The first line of input contains one integer $ n $ ( $ 1

Print a single integer — the number of regions on the plane.

For the first example, For the second example, For the third example,