import ast
while True:
try:
string = raw_input('What numbers should I average? ')
words = string.split()
numbers = [ast.literal_eval(word) for word in words]
total = sum(numbers)
count = len(numbers)
average = 1.0 * total / count
print 'The average is', average
raw_input('Press enter to quit.')
break
except:
print 'Please only give me numbers.'