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


# 0除算させないように
a *= 10 ** 32
b *= 10 ** 32
c *= 10 ** 32
a += 1
b += 1
c += 1

pa = a / (a + b + c)
pb = b / (a + b + c)
pc = c / (a + b + c)


def solve(a, b, c, pa, pb, pc):
    pba = 1 / 2
    pbb = 0
    pbc = 1
    ans1 = pba * pa / (pba * pa + pbb * pb + pbc * pc)
    ans2 = pbc * pc / (pba * pa + pbb * pb + pbc * pc)
    return max(ans1, ans2)


ans = max(solve(a, b, c, pa, pb, pc), solve(b, c, a, pc, pb, pa), solve(c, a, b, pc, pa, pb))
print(ans)