P, Q, R = map(int, input().split())

p = [P / (P + Q + R), Q / (P + Q + R), R / (P + Q + R)]
res = 0.0

#STAYする
for i in range(3):
    res = max(res, p[i])

#CHANGEする
for i in range(3):
    res = max(res, 1 - p[i])

print(res)