class point(object):
def __init__(self, x, y):
self.x = x
self.y = y
def distance(self, point):
return ((self.x - point.x)**2 + (self.y - point.y)**2)**0.5
ab, r, AB, R = point(9, 4), 2.5, point(4.5, 5.5), 3.5
pt = point(float(input()), float(input()))
print((pt.distance(ab)