Crickets chirp by rubbing their wings over each other. Yet it is only the males of the species that make this noise — they do so to attract mates. Therefore, when you're happily listening to the soothing sound of crickets chirping, you're actually eavesdropping on a courting ritual meant to warn off other lust-filled male crickets and to draw interested females to the ones doing the serenading.

The notion that counting the chirps of crickets can serve as an informal way of working out the temperature is not new. It was originally formulated in 1897 by physicist Amos Dolbear1 in an article called "The Cricket as a Thermometer2". Dolbear originally stated that the outdoor temperature determines the number of cricket calls one would hear. Over the years, his way of looking at this relationship was turned around — people now count the chirps to get the temperature rather than consult the thermometer to figure out how many cricket calls they will hear. Dolbear's Law expresses the relationship as the following formula, which provides a way to estimate the temperature $$T_F$$ in degrees Fahrenheit from the number of chirps per minute $$N_{60}$$: \[T_F = 50 + \left(\frac{N_{60} - 40}{4}\right)\] Reformulated to give the temperature in degrees Celsius (°C), it is: \[T_C = 10 + \left(\frac{N_{60} - 40}{7}\right)\] The above formulae are expressed in terms of integers to make them easier to remember — they are not intended to be exact. In popular culture, Dolbear's Law was referenced in an episode of the British comedy show QI (starts at time 28:36).


The number of observed chirps per minute $$N_{60} \in \mathbb{N}$$.


A line containing the text temperature (Fahrenheit): TF with $$T_F$$ the temperature in degrees Fahrenheit according to Dolbear's Law, given the number of observed chirps per minute $$N_{60}$$ as read from the input. A second line giving the same temperature $$T_C$$ but expressed in degrees Celsius.





temperature (Fahrenheit): 50.75
temperature (Celsius): 10.428571428571429