# 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.

N = 1000
s = 0
for i in range(N):
    if i%3 == 0:
        s = s + i
    elif i%5 == 0:
        s = s + i

print(s)
