/* Check cf5-opt.vim defs.
VIM: let g:lcppflags="-std=c++11 -O2 -pthread"
VIM: let g:wcppflags="/O2 /EHsc /DWIN32"
*/
#include <iostream>

/*
Multiples of 3 and 5
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.

Solution:
233168
*/

/*
	Sum of all numbers below n multiple of m
*/
int sum(int n, int m )
{
	int c = n/m;
	return m*c*(c+1)/2;
}

int main ( void )
{
	const int l = 999;
	const int o1 = 3;
	const int o2 = 5;
	int s =	sum( l, o1 ) + sum( l, o2 ) - sum( l, o1*o2 );
	std::cout << s << std::endl;

	return 0;
}