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Биномиальный коэффициент

C0n + ... + Cnn

Given a non-negative integer n, find the sum of binomial coefficients

prb9892.gif

Input

One non-negative integer n (n60).

Output

Print the value of the sum.

Time limit 1 second
Memory limit 128 MiB
Input example #1
2
Output example #1
4
Author Mykhailo Medvediev