# Cel2FahrWithValidation Example
# Convert Celsius temperature to Fahrenheit.
# Validate the input to make sure that it is greater
# than absolute zero (-273 deg F).

# Import sys module to be able to use sys.exit( ).
import sys

cel = float(input("Enter a Celsius temperature: "))

# Validate input.
if cel < 273.0:
    print("Celsius temperature must be greater or equal to absolute zero.")
    sys.exit( )
    
fahr = 9 * cel / 5 + 32
print("Fahrenheit temperature:", fahr)