class Main {
  public static void main(String[] args) {
      
    int N = 1000;
    int result = sum(3, N-1) + sum(5, N-1) - sum(15, N-1);
    
    System.out.println(result);
  }
  
  public static int sum(int n, int N) {
      return n * (N/n) * (N/n + 1)/2;
  }
}