Disk

Time Limit: 2 Seconds
Memory Limit: 65536 KB

Given N disks, try to calculate the area that is covered by them.

**Input**

The first line contains only the integer N (1 <= N <= 4).

The following N lines contain information about the N disks.

Xi Yi Ri (3 floating-point numbers)

Here (Xi, Yi) is the centre of the ith disk and Ri (0 < Ri <= 1) is its
radius.

There are several testcases, so process to the end-of-file.

**Output**

For each testcase, output a line containing only the area that is covered by
the disks.

The result should be a floating-point number, having 3 digits after radix point.

**Sample Input**

1

0 0 1

2

0 0 1

1 0 1

** Sample Output**

3.142

5.055

Author:

**SHI, Xiaohan**
Source:

**ZOJ Monthly, June 2003**
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