Project Euler 1 - Multiples of 3 and 5

/*
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.
*/

#include <iostream>
#include <stdlib.h>
#include <vector>
#include <algorithm>

using namespace std;

int main()
{
    vector <int> multiples = vector <int> ();
    for(int i=3; i<1000; i++){
        if(i % 3 ==0 || i % 5 == 0){
            multiples.push_back(i);
        }
    }
    int sum = 0;
    for(unsigned int i =0; i<multiples.size(); i++){
        sum += multiples[i];
    }
    cout << "Sum = " << sum << endl;
    return 0;
}