#include<iostream>
#include<string>

using namespace std;

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