A,B,C = list(map(int, input().split()))

def heron(A, B, C):
  s = (A + B + C) / 2
  S = (s * (s - A) * (s - B) * (s - C)) ** (1 / 2)
  return S
def hankei(A, B, C, S):
  return 2 * S / (A + B + C)

S = heron(A, B, C)
r = hankei(A, B, C, S)
print(r)