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Problem 1091 Zig-Zag Lines

Accept: 372    Submit: 675
Time Limit: 1000 mSec    Memory Limit : 32768 KB

Problem Description

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

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