import math

# DIRECTIONS GO BACKWARDS IN THIS GAME
# WHY NOT
def get_direction(x1,y1,x2,y2):
	dx,dy=x2-x1,y2-y1
	if dx==0: return math.pi*(2-sign(dy))/2
	t=math.atan(dy/dx)
	return t+math.pi*(sign(dx)<0)

def sign(num):
	return (num>=0)*2-1-(num==0)