1083 - Union

Time Limit: 10s Memory Limit: 128MB

Submissions: 389 Solved: 138
Description
Given two simple polygons, you are asked to calculate the area of their union.
Input
There is a single case: In the first line: two integers n1 and n2, indicating the number of the vertex of the two polygons(3 <= n1, n2 <= 500). In the following n1 lines: each line contains two integers xi and yi, the coordinate of the i-th vertex of the first polygon. In the following n2 lines: each line contains two integers xi and yi, the coordinate of the i-th vertex of the second polygon. All the vertices are given in the counter-clockwise order. All the xs and the ys are in the range of [-20000, 20000].
Output
A single number: the area of the union with a precision of two numbers after the decimal point.
Sample Input
4 4
1 0
2 0
2 3
1 3
0 1
3 1
3 2
0 2
Sample Output
5.00
Hint
Source
Isun