2 shunfurh shunfurh 于 2017.09.10 18:47 提问

Count the Regions

What's the maximum number of regions definable by N zig-zag lines, each of which consists of two parallel infinite half-lines joined by a straight line segment?

Here is an example of 2 zig-zag lines yield 12 regions at the most.

Input

The input consists of a sequence of N (<= 10000), which is the number of the zig-zag lines, one per line.

Output

For each N, you should output the number of the maximum regions.

Sample Input

1
2

Sample Output

2
12

1个回答

devmiao
devmiao   Ds   Rxr 2017.09.27 21:52
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