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


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

if a * b * c == 0:
    print(max(a, b, c) / (a + b + c))
    exit()

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)