#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);

bool is_prime (int n){
	if(n == 2) return true;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0){ 
			return false;
		}
	}

	if (n != 1) return true;
	else return false;
}

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

	// input
	ll n;
	cin >> n;
	vl sosu = {};
	for (int i = 2; i * i <= n; ++i){
		// cerr <<"i: "<< i << "\n" ;
		if(!is_prime(i)) continue;
		sosu.push_back(i);
	}

	ll ans = 0;
	for (auto x : sosu){
		ll temp = x;
		while(true){
			temp *= x;
			if(temp <= n){
				ans += temp;
				// cerr <<"temp: "<< temp << "\n" ;
			}
		}
	}
	cout << ans << endl;
	return 0;
}