Find the sum 2#11433
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Find the sum 2

1 second
128 megabytes
Very easy

For the given natural number find the sum

\dfrac{1}{\sin 1} + \dfrac{1}{\sin 1 + \sin 2} + \ldots + \dfrac{1}{\sin 1 + \sin 2 + \ldots + \sin n}

Input

One natural number n\:(n \le 1000).

Output

Print the value of the sum with decimal digits.

Examples

Example 1

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