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Grazed Grains

Interview

Time limit3sMemory limit1024 MB

Summary
Given up to 10 circles, output the area of their union within 10% relative error, which Monte Carlo sampling can approximate.
Level

Medium5 of 10

Topics
Geometry, Probability, Implementation, Brute force
Solved
No attempts yet

Problem

This year, there have been unusually many UFO sightings reported. Nobody knows if they are caused by optical illusions, weather phenomena, or secret technology being tested by foreign powers (terrestrial or not). UFO enthusiasts across the world rejoice, and speculations run wild. But someone who is not impressed is the farmer Celeste. Her large grain field has repeatedly been used as a landing site by the UFOs, destroying her crops. Celeste would like to bring whoever is responsible to justice, but before she can do so she must assess the damage caused by the unidentified flying offenders.

In total nn circular UFOs have landed in Celeste's field. The iith one left a crop circle which destroyed all crops within radius r_ir\_i of the point x_i,y_ix\_i, y\_i. The field is very large, so you can assume that it extends infinitely in all directions. Your task is to estimate the total area of crops destroyed by the UFOs. Celeste only needs a rough estimate of the true answer, and your answer will be counted as correct if its relative error is less than 10%10\%.

Input

The first line of input contains one integer nn (1≤n≤101 \leq n \leq 10), the number of UFOs. Then follow nn lines, the iith of which contains the three integers x_ix\_i, y_iy\_i, and r_ir\_i (0≤x_i,y_i≤100 \leq x\_i, y\_i \leq 10, 1≤r_i≤101 \leq r\_i \leq 10), describing the crop circle left by the iith UFO.

Output

Output the total area covered by the crop circles in the input, with a relative error of at most 1/101/10.

Examples2

  1. Example 1

    Input
    1
    0 0 1
    
    Expected output
    3.1415926535
    
  2. Example 2

    Input
    4
    0 0 2
    1 0 1
    2 2 2
    10 10 1
    
    Expected output
    25.991148