#
#  Read the values from the user
#

values = []
x = input("Enter a value (negative to quit): ")

while (x >= 0):
   values.append(x)
   x = input("Enter a value (negative to quit): ")

#
#  Sort the values
#
values.sort()

#
#  Report the median
#
#  if the length of the list is odd, report the middle value
#  if the length of the list is even, report the average of the two middle 
#  values
#
if (len(values) == 0):
   print "No values were entered"
elif (len(values) % 2 == 1):
   print "The median value is",values[len(values) / 2]
else:  # (len(values) % 2 == 0)
   print "The median value is",(values[len(values) / 2] + values[len(values) / 2 - 1]) / 2.0