/**
 * Title:
 * Url:
 */
#include<bits/stdc++.h>

using namespace std;

#define ll long long

int main() {

    int n; cin >> n;
    ll sum = 0;
    for(int i=0; i<n; i++) {
        if(!(i%3==0||i%5==0)) {
            sum += i;
        } 
    }
    cout << sum << endl;

    return 0;
}