Some bugs in the validator were fixed. The problem was rejudged. 299 WA submits turned to AC and 84 AC submits turned to WA. If you will find new bugs, please, write to timus_support (at) acm.timus.ru.

Edited by author 09.09.2010 10:57

To those who have WA at 2 after rejudge:
The ending point MUST have positive (STRICTLY) coordinates.

Try this testcase:
1
1 1 2 2 4
2 3
to see if your answer satisfies the condition.

Thx a LOOOOT of @198808xc.  I got AC .

if c0  less than all of other delay times:
   x = 0.003 ;
   y = sqrt(L*L - x*x)