import sys

time = float(input("Length of time (as a number): "))
if time < 0:
    print('Invalid time.  Time must be a positive number.')
    sys.exit()
orig_time = time

from_unit = input('Unit of time (second, minute, hour, day): ').lower()
#convert from_unit into seconds
if from_unit == 'minute':
    time *= 60
elif from_unit == 'hour':
    time *= 3600
elif from_unit == 'day':
    time *= 86400
else:
    print('Invalid unit of time')
    sys.exit()

to_unit = input('Convert to (second, minute, hour, day): ')
#convert from seconds into to_unit
if to_unit == 'minute':
    time /= 60
elif to_unit == 'hour':
    time /= 3600
elif to_unit == 'day':
    time /= 86400
else:
    print('Invalid unit of time')
    sys.exit()

time = round(time, 4) #format(time, '.4f')
print(orig_time, from_unit, '=', time, to_unit)