#include "bits/stdc++.h"
using namespace std;
#define  rep(i,s,t) for (auto i=s; i != t; ++i)
#define rrep(i,s,t) for (auto i=t; i-- != s;)
typedef long long ll;
// constexpr auto inf = numeric_limits<ll>::max() / 2;
constexpr bool chmin(auto &a, auto const &x) { return a > x ? a = x, true : false; }
constexpr bool chmax(auto &a, auto const &x) { return a < x ? a = x, true : false; }
// constexpr auto ascii_lowercase = "qwertyuiopasdfghjklzxcvbnm"sv;

int main() {
  ll n;
  cin >> n;

  vector<bool> prime(100000+10, true);
  ll ans=0;
  for (ll p=2; p*p <= n; ++p) {
    if (not prime[p]) continue;
    for (ll q=p*p; q < ssize(prime); q += p)
      prime[q] = false;
    for (ll q=p*p; q <= n; q *= p)
      ans += q;
  }

  cout << ans << endl;
}