#include <bits/stdc++.h>
using namespace std;

int main () {
  	int n, total;
   	cin >> n;
  	total = 0;
	for (int i = 0;i<n;i++) {
    	if (i % 3 != 0 && i % 5 != 0) total += i;
    }
  	cout << total << endl;
}