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

int main() {
  ll N;
  cin >> N;
  ll ans = 0;
  for (ll i = 0; i < N; i++) {
    if (i%3 == 0) {
      ans = ans;
    }
    else if (i%5 == 0) {
      ans = ans;
    }
    else {
      ans += i;
    }
  }
  cout << ans << endl;
}