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Competitions

PP2. Week 1: March 1 - 7

Find the sum

Given number n, find the sum

prb8546.gif

Input

One positive integer n (n ≤ 1000).

Output

Print the sum with 6 decimal digits.

Time limit 1 second
Memory limit 128 MiB
Input example #1
5
Output example #1
0.833333
Input example #2
12
Output example #2
0.923077