|A Fountain of Life is a special fountain that produces the elixir of life at a constant speed of elixir liters per second. A dark mage managed to cast a Curse of Death on the Fountain so in addition to the elixir it now produces a deadly poison at a constant speed of poison liters per second. Both the poison and elixir are collected in an infinitely large pool around the Fountain and form a mixture. The mixture will become deadly once the percentage of poison in the mixture is at least 50%. Your task is to calculate the time at which the mixture will become deadly. At the beginning (0-th second) the pool contains pool liters of 100% elixir.|
Your program must return a double, the time in seconds at which the mixture becomes deadly. If the mixture never becomes deadly, return -1.0.
|-||The returned value must be accurate to within a relative or absolute value of 1E-9.|
|-||elixir will be between 1 and 10000, inclusive.|
|-||poison will be between 1 and 10000, inclusive.|
|-||pool will be between 1 and 10000, inclusive.|