#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() {
  ll n, ans = 0; cin >> n;
  rep(i, n) {
    if ((i+1) % 3 == 0|| (i+1) % 5 == 0) continue;
    ans += i+1;
  }
  cout << ans << endl;
  return 0;
}