#P630C. Lucky Numbers
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ID: 3456
Type: RemoteJudge
1000ms
64MiB
Tried: 0
Accepted: 0
Difficulty: (None)
Uploaded By:
Hydro
Tags> Lucky Numbers
No submission language available for this problem.
Description
The numbers of all offices in the new building of the Tax Office of IT City will have lucky numbers.
Lucky number is a number that consists of digits 7 and 8 only. Find the maximum number of offices in the new building of the Tax Office given that a door-plate can hold a number not longer than n digits.
The only line of input contains one integer n (1 ≤ n ≤ 55) — the maximum length of a number that a door-plate can hold.
Output one integer — the maximum number of offices, than can have unique lucky numbers not longer than n digits.
Input
The only line of input contains one integer n (1 ≤ n ≤ 55) — the maximum length of a number that a door-plate can hold.
Output
Output one integer — the maximum number of offices, than can have unique lucky numbers not longer than n digits.
Samples
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