#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); i++)
using namespace std;
using ll = long long;
using P = pair <int, int>;

int main() {
  int64_t N;
  cin >> N;

  int64_t ans = 0;

  rep(i, N){
    if (i % 3 != 0 && i % 5 != 0) ans += i;
  }

  cout << ans << endl;

}
