P, Q, R = map(int, input().split())
s = P + Q + R
p, q, r = P/s, Q/s, R/s

def calc(a, b, c): # a を選んだ場合の期待値
    re = 0
    re += a * (1/2) * (1 if P >= R * 2 else 0)
    re += a * (1/2) * (1 if P >= Q * 2 else 0)
    re += b * (0 if P >= Q * 2 else 1)
    re += c * (0 if P >= R * 2 else 1)
    return re

print(max(calc(p, q, r), calc(q, r, p), calc(r, p, q)))