#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vs = vector<string>;
using vp = vector<pair<int, int>>;

#define rep(i, s, n) for (int i = s; i < (int)(n); i++)
#define sz(x) ((int)(x).size())
constexpr int INFI = 1001001001;
constexpr ll INFL = (1LL << 60);

vl get_primes(ll n) {
	ll limit = sqrt(n) + 1;
	vector<bool> is_prime(limit + 1, true);
	is_prime[0] = is_prime[1] = false;

	for (ll i = 2; i * i <= limit; i++) {
		if (!is_prime[i]) continue;
		for (ll j = i * i; j <= limit; j += i){
			is_prime[j] = false;
		}
	}

	vl primes;
	for (ll i = 2; i <= limit; i++){
		if (is_prime[i]) primes.push_back(i);
	}
	return primes;
}

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

	// input
	ll n, ans = 0;
	cin >> n;

	vl primes = get_primes(n);

	for (auto x : primes){
		ll temp = x;
		while(true){
			temp *= x;
			if(temp <= n){
				ans += temp;
			}
			else break;
		}
	}
	cout << ans << endl;
	return 0;
}