Power of two#119

Power of two

1 second
128 megabytes
Medium

Given a sequence of powers of , i.e., the numbers 2, 4, 8, \ldots, 2^n, written one after another in a single line without any spaces, determine the value of .

Input

A single line contains (1 \leq n \leq 1000) consecutive powers of written without any spaces.

Output

Print the value of .

Examples

Example 1

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