#include <bits/stdc++.h>
using ll = long long;
using namespace std;
int main() {
    int n;
    cin >> n;
    
    ll total = 0;
    for (int i = 0; i < n; i++) {
        if (i % 3 != 0 && i % 5 != 0)
            total += i;
    }

    cout << total << endl;
    
    return 0;
}
