Area of Intersection between Two Circles

Write a program which prints the area of intersection between given circles $c1$ and $c2$.

Input

The input is given in the following format.

$c1x\; c1y\; c1r$
$c2x\; c2y\; c2r$

$c1x$, $c1y$ and $c1r$ represent the coordinate and radius of the first circle. $c2x$, $c2y$ and $c2r$ represent the coordinate and radius of the second circle. All input values are given in integers.

Output

Output the area in a line. The output values should be in a decimal fraction with an error less than 0.000001.

Constraints

• $-10,000 \leq c1x, c1y, c2x, c2y \leq 10,000$
• $1 \leq c1r, c2r \leq 10,000$

Sample Input and Output

Sample Input 1

0 0 1
2 0 2

Sample Output 1

1.40306643968573875104

Sample Input 2

1 0 1
0 0 3

Sample Output 2

3.14159265358979311600