# bisiter-q2
# Sections 1-5, Q.2, p.12, p.245
#inputs: 1 2

def f(x):
  return x*x*x - x - 1

def bis(a, b):
  eps = 1e-9
  faneg = (f(a) < 0.0)
  while abs(a-b) >= eps:
    m = (a+b)/2.0
    y = f(m)
    if (y < 0.0) == faneg:
      a = m
    else:
      b = m
  return m

a, b = map(float, input("a b=? ").split())
print( bis(a,b))