#include <bits/stdc++.h>

using namespace std;

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