how you people are getting 0.001
Though I have used nlog(2*MAX_X) solution I am getting around 0.015 to 0.031
My approach :
1 . Make all coordinates > 0 and xi = MAX_X - x1+1
2 . process the points in increasing y and for same y increasing x
3 . maintain BIT [0..MAX_X] and do query and update in log

The 0.015 is the minimal allowed time now. The peoples, who attend 0.001 have sent there solutions later.
*sorry for my bad english