P, Q, R = map(int, input().split())
S = P + Q + R
p = [P/S, Q/S, R/S]

max_prob = 0.0
for pi in p:
    current_max = max(pi, 1 - pi)
    if current_max > max_prob:
        max_prob = current_max

print("{0:.12f}".format(max_prob))