A Simple Problem

Time Limit: 1000 ms

Memory Limit: 65535 ms

Description

The Problem is simple . Give some inequalities like ax+by+c<0 in the form of a,b,c . Now your task is to calculate the area of the intersection of those inequalities.

Input

First a number n(n<1000) as the number of the inequalities . Then the next n lines each contains three numbers a , b , c ( 0 < a,b,c <200 )described above . The input ends with a 0 .

Output

Each case print a number (the area) , the format is as sample output . If the area is not closed , just output -1.00 . (two numbers after point)

Sample Input

1
1 1 1
4
0 -1 0
0 1 -1
-1 0 0
1 0 -1
3
1 0 -1
0 1 -1
-1 -1 1
0

Sample Output

-1.00
1.00
0.50

Hint

Source

xiaoyoulei

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