# In this exercise you will reverse the process 
# described in the previous exercise. 
# Develop a program that begins by reading a number 
# of seconds from the user. Then your program should 
# display the equivalent amount of time in the 
# form D:HH:MM:SS, where D, HH, MM, and SS represent 
# days, hours, minutes and sec- onds respectively. 
# The hours, minutes and seconds should all be formatted so that
# they occupy exactly two digits, with a leading 0 displayed if necessary.