Time Limit: 1000 ms
Memory Limit: 65535 ms
Bruce Force is standing in the forest. He wonders what is the tree trunk the farthest away which is not blocked from his view by other tree trunks.
Bruce has made a map of the trees in the forest. The map shows his current position as the origin of a cartesian coordinate system. Tree i is shown on the map as a circle with the center (xi, yi) and radius ri. You may assume that a tree trunk is visible if and only if there exists a line segment on the map from the origin (0,0) to a point on the border of the circle representing the tree trunk, where the line segment does not intersect or touch another circle.