#include<bits/stdc++.h>
using namespace std;
typedef long long int ll;
ll fun(ll x){
    return x*(x+1)/2;
}
int main (){
    ll n;cin >> n;

    ll sum = fun(n);
    for(int i=1;i<=n;i++){
        if(i%3==0||i%5==0||i%15==0)sum-=i;
    }
    cout<<sum<<endl;
    return 0;
}
