#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define rep(i, r) for(int i = 0; i < (int)(r); i++)
#define reap(i, k, r) for(ll i = (ll)(k); i < (ll)(r); i++)
#define ALL(x) std::begin(x), std::end(x)
#define rALL(x) std::rbegin(x), std::rend(x)
#define MOD 998244353
using namespace std;
int main(){
    ll ans = 0;
    ll N; cin >> N;
    ll ma = sqrtl(N) / 1 + 2;
    auto isprime = [&](ll x) -> ll{
        for(ll i = 2; i * i <= x; i++){
            if(x % i == 0){
                return 0;
            }
        }
        return 1;
    };
    reap(i, 2, ma){
        ll is = isprime(i);
        if(is){
            ll now = i;
            while(true){
                now *= i;
                if(now > N)break;
                ans += now;
            }
        }
    }
    cout << ans << endl;
}