from math import sqrt


def area(a, b, c):
    s = (a + b + c) / 2
    t = s * (s-a) * (s-b) * (s-c)
    return sqrt(t)


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

s = area(A, B, C)
ans = 2 * s / (A + B + C)
print(ans)