#include <iostream>
using namespace std;

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