#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() {
  int n;
  cin >> n;
  long long int sum = 0;
  rep(i,n) {
    if (i%3!=0 && i%5!=0) sum += i;
  }

  cout << sum << endl;
}
