a, b, c = map(int, input().split())

# S = 1 / 2 * (a + b + c) * r らしいです！
# r = 2 * S / (a + b + c)

s = (a + b + c) / 2
S = (s*(s-a)*(s-b)*(s-c))**.5
print(2 * S / (a + b + c))