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Problems

Find the sum 2

Find the sum 2

Time limit 1 second
Memory limit 128 MiB

For the given value of n find the sum

\dfrac{1}{sin\:1} + \dfrac{1}{sin\:1 + sin\:2} + ... + \dfrac{1}{sin\:1 + sin\:2 + ... + sin\:n}

Input data

One integer n\:(n \le 1000).

Output data

Print the value of the sum with 6 decimal digits.

Examples

Input example #1
3
Output example #1
2.288145