#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main() {
    ll n;
    cin>>n;
    ll ans = 0;
    ll co = 0;
    for(ll i = 1;;i++){
        if(co==n){
            break;
        }
        co++;
        if(i%3!=0&&i%5!=0){
            ans+=i;
        }
    }
    cout<<ans<<endl;
}