#include <iostream>
using namespace std;
using ll = long long;

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