FENCE1  Build a Fence
There is a wall in your backyard. It is so long that you can’t see its endpoints. You want to build a fence of length L such that the area enclosed between the wall and the fence is maximized. The fence can be of arbitrary shape, but only its two endpoints may touch the wall.
Input
The input consists of several test cases.
For every test case, there is only one integer L (1<=L<=100), indicating the length of the fence.
The input ends with L=0.
Output
For each test case, output one line containing the largest area. Your answer should be rounded to 2 digits after the decimal point.
Example
Input: 1 0 Output: 0.16
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baadshah_:
20160622 08:54:33
trick printf("%.2f\n",ans); 

CounterNormalize:
20160111 02:30:41
for those getting WA in C++


rpc1:
20150519 20:18:47
Imagine a very long straight ruler and a piece of smallish rope. The rope is tied to the ruler at one end and loose at the other. Now connect the other end of the rope to the ruler and you'd get a shape with a straight bottom (made of the ruler itself) and a curvy top (made by the rope). This shape has an area, what is its maximum area given the length of the rope? 
Added by:  Fudan University Problem Setters 
Date:  20090523 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: C99 ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  Fudan University Local Contest #1, practise session 