#!/usr/bin/env python
# encoding: utf-8


def problem1():
    """
    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.
    """
    result = 0
    for i in range(1, 1000):
        if((i % 3 == 0) or (i % 5 == 0)):
            result += i
    return result

if __name__ == "__main__":
    print problem1()
