#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); ++i)
bool p[1 << 17];
using ll = long long;
signed main() {
  cin.tie(0)->sync_with_stdio(0);
  rep(i, 1 << 17) p[i] = 1;
  p[0] = p[1] = 0;
  rep(i, 1 << 17) {
    if (!p[i]) continue;
    for (int j = 2 * i; j < 1 << 17; j += i) p[j] = 0;
  }
  vector<ll> primes;
  rep(i, 1 << 17) if (p[i]) primes.emplace_back(i);
  ll ans = 0, N;
  cin >> N;
  for (ll prime : primes) {
    ll cur = prime * prime;
    while (cur <= N) {
      ans += cur;
      cur *= prime;
    }
  }
  cout << ans << endl;
}