def f(a,b,c):
    if a > b:
        max = a
    else:
        max = b

    if max < c:
        max = c
    
    return max


nums = input()
lst = nums.split()
a = int(lst[0])
b = int(lst[1])
c = int(lst[2])

m = f(a + b, b, c) / (f(a, b + c, c) + f(a, b, b + c))
print(f'{m:.2f}')