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

#define ll long long int
#define vi vector<int>

int main() {

    ll N;
    cin >> N;

    ll ans = 0;
    for (int i = 0; i < N; ++i) {
        if (i%3 == 0 || i%5 == 0) {
            continue;
        }
        ans += i;
    }

    cout << ans << endl;

    return 0;
}
