Noise-induced hearing loss is an insidious threat where loss of hearing occurs in the cochlea, for it contains hair cells that can be damaged by excessive sound levels . Both the severity and the moment it occurs depend on the intensity and the duration of noise. A rule of thumb that is used by audiologists, says that one may work a maximum of 8 hours a day in an environment of 80 dB to avoid the risk of noise-induced hearing loss. For every three decibels that is added onto the initial 80, one needs to halve the duration of exposure. Recently, a sound level up to 118 dB was measured in some movie theaters. According to the rule of thumb, one risks permanent damage after an exposure of more than 7 seconds to this environment. Long lasting exposure to an environment of less than 80 dB normally doesn't result in any hearing loss.

Assignment

Write a function maximum_exposure to which a real value should be passed as an argument. This value represents a sound level in decibel. The function should print the duration of exposure (a real number that expresses an amount of seconds) that is recommended for the sound level given. Use the rule of thumb. Basically, the function should print the value -1 if the given sound level is less than 80 dB (this value corresponds with an unlimited exposure). For a given sound within the interval $$[80,83[$$ dB the function should print a value that corresponds with a duration of 8 hours. For every following interval of 3 dB, this duration should be halved ($$[83,86[\ \rightarrow$$ 4 hours, $$[86,89[\ \rightarrow$$ 2 hours, $$[89,92[\ \rightarrow$$ 1 hour, …).

Example

>>> maximum_exposure(40)
-1.0
>>> maximum_exposure(60)
-1.0
>>> maximum_exposure(75)
-1.0
>>> maximum_exposure(80)
28800.0
>>> maximum_exposure(86)
7200.0
>>> maximum_exposure(90)
3600.0
>>> maximum_exposure(95)
900.0
>>> maximum_exposure(97)
900.0
>>> maximum_exposure(105)
112.5
>>> maximum_exposure(107)
56.25
>>> maximum_exposure(118)
7.03125
>>> maximum_exposure(115)
14.0625
>>> maximum_exposure(120)
3.515625