public class MyClass {
public static int Sum(int n) {
return n * (n + 1) / 2;
}
public static void main(String args[]) {
int below1000 = 999;
int sum = 3 * Sum((int)(below1000 / 3)) + 5 * Sum((int)(below1000 / 5)) - (3 * 5) * Sum((int)(below1000 / 15));
System.out.print("sum = " + sum);
}
}
/*
run:
sum = 233168
*/