#include <iostream>
using namespace std;

int main() {
	int N;
	cin >> N;

	long long sum = 0;
	for (int i = 0; i < N; ++i) {
		if (i % 3 != 0 && i % 5 != 0) {
			sum += i;
		}
	}

	cout << sum << endl;

	return 0;
}