Description

Given three points P1(x1,y1),P2(x2,y2),P3(x3,y3) , you are to calculate the area surrounded by the three points. If the three points are collinear, the area is zero.

Input

The input file contains several test case, each test case consists of six integers x1,y1,x2,y2,x3,y3, (0<=xi<=10000 and 0<=yi<=10000)which are the coordinates of the triangle’s three vertexes. Process to the end of the file.

Output

For each test case, output a line the area of the corresponding triangle,which should be printed accurately rounded to two decimals.

Sample

Input

1 1 2 2 3 3
0 0 2 0 0 3

Output

0.00
3.00

Source: Limitfan