3660: Star
Time Limit: 2 Sec Memory Limit: 256 MBSubmit: 0 Solved: 0
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Description
time limit per test
2 secondsmemory limit per test
256 megabytesinput
standard inputoutput
standard output
Input
The input contains a single integer a (1≤a≤18257).
Output
Print a single integer output (1≤output≤2·109).
Examples
Input
2
Output
13