#include <bits/stdc++.h>
#ifdef DEBUG
#include "cpp-dump/cpp-dump.hpp"
#define dump(...) cpp_dump(__VA_ARGS__)
#else
#define dump(...)
#endif
using namespace std;
typedef long long ll;
vector<ll> Eratosthenes_list(ll N) {
    vector<bool> isprime(N + 1, true);

    isprime[0] = isprime[1] = false;

    // ふるい
    for (ll p = 2; p <= N; ++p) {
        if (!isprime[p]) continue;

        for (ll q = p * 2; q <= N; q += p) {
            isprime[q] = false;
        }
    }

    vector<ll> prime_list;
    for (ll i = 0; i < isprime.size(); ++i) {
        if (isprime[i]) prime_list.push_back(i);
    }

    return prime_list;
}

void solve() {
    ll n;
    cin >> n;

    vector<ll> sosu = Eratosthenes_list(500002);
    ll ans = 0;
    for (ll i = 0; i < sosu.size(); ++i) {
        if (sosu[i] * sosu[i] > n) break;
        ll tmp = sosu[i];
        while (tmp <= n) {
            tmp *= sosu[i];
            if (tmp > n) break;
            ans += tmp;
        }
    }
    cout << ans << endl;
}

int main() {
    solve();
    return 0;
}