A, B, X, Y = map(int, input().split())

if X * B <= Y * A:
    max_volume = (X * (A + B)) / A
else:
    max_volume = (Y * (A + B)) / B

# Format the output to handle decimal precision and trailing zeros
formatted = "{0:.12f}".format(max_volume).rstrip('0').rstrip('.') if '.' in "{0:.12f}".format(max_volume) else "{0:.0f}".format(max_volume)
print(formatted)