'''
Problem 1

If we list all the natural numbers below 10 
that are multiples of 3 or 5, we get 3, 5, 6 and 9. 
The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.
'''

print sum(filter(lambda x: x%3==0 or x%5==0, range(1,1000)))