Олимпиадный тренинг

Задача 38673. Arc length


Input
Seven numbers – coordinates of the center and radius of a circle (possibly degenerate) and real coordinates of two points on it, up to the fifth decimal place.

Imprint
One number – the length of the smaller arc of the circle enclosed between the specified points.
 
Examples
# Input Output
1 0 0 1 0 1 1 0 1.57080