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Problems

Sum of values

Sum of values

Time limit 1 second
Memory limit 128 MiB

Find the sum of values for the function

prb2892

in some integers.

Input data

First line contains the number of points n (1n50). Next line contains n integers x[1], x[2], ..., x[n] - the points where the function must be calculated and summed up (0 ≤ |x[i]| ≤ 10^9).

Output data

Print one number - the sum of function values f(x) at given points. The answer is correct if its accuracy is no less than 10^(-9).

Examples

Input example #1
3
1 2 3
Output example #1
7.833333333333333
Input example #2
2
1 -1
Output example #2
0
Source 2012 Kharkiv, Winter School, Day of Sergey Kopelovich, Problem L