#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <map>
#include <numeric>
using namespace std;
typedef long long ll;

int main(){
    int n;cin>>n;
    ll ans=0;
    for(int i=1;i<=n;i++){
        if(i%3==0||i%5==0)continue;
        ans+=i*1ll;
    }
    cout<<ans;
}