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

int main() {
  int n;
  int sum = 0;
  cin >> n;
  
  for(i = 0; i < n; i++)
  {
    if(i%3 == 0 || i%5 == 0)
    {
    }
    else
    {
      sum += i;
    }
  }
  
  cout << sum << endl;
}