Green spot - 2

Two projectors of the round form form on a wall two spots, one - blue, and the second – yellow color. To define the area of a spot of green color which will turn out at imposing two spots.

Input

In the first line coordinates of the center of one spot contain: X_1, Y_1 and its radius R_1, and in the second – coordinates of the center of second spot X_2, Y_2 and its radius R_2. (|X_i|, |Y_i|, R_i <= 10^6)

Output

In one line a singular: the required area of a green spot deduced with accuracy of 3 signs after a decimal point, received by rules of mathematical calculations.

Examples