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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll N;
    cin>>N;
    ll an=0;
    for(ll p=2;p*p<=N;p++){
        bool OK=1;
        for(ll x=2;x*x<=p;x++)if(p%x==0){
            OK=0;
            break;
        }
        if(!OK)continue;
        ll r=p;
        while(r*p<=N){
            r*=p;
            an+=r;
        }
    }
    cout<<an<<"\n";

}