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

int main()
{
    ll N;
    cin >> N;

    ll sum = 0;
    for (size_t i = 0; i < N; i++)
    {
        if (i % 3 == 0 || i % 5 == 0)
        {
            continue;
        }
        sum += i;
    }
    cout << sum << endl;
}
