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Problems

C0n + ... + Cnn

C0n + ... + Cnn

Time limit 1 second
Memory limit 128 MiB

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

C_n^{0} + C_n^{1} + ... + C_n^{n}

Input data

One non-negative integer n\:(n \le 60).

Output data

Print the value of the sum.

Examples

Input example #1
2
Output example #1
4
Author Mykhailo Medvediev