def pad(num):
   '''num is an int.  If num is a 1-digit number, then
       return num as a string with a 0 prepended on it.
       otherwise, return num as a string.'''

   if num < 10:
       return "0" + str(num)
   else:
       return str(num)

def printTimes():
   for hours in range(24):
      for mins in range(60):
         for secs in range(60):
            print(pad(hours),":",pad(mins),":",pad(secs),sep='')
            

def main():
    printTimes()

main()