#include <bits/stdc++.h>
using namespace std;

int main() {
  long long N, Ans = 0; cin >> N;
  vector<bool> Eratosthenes(100000, true);
  for (int i = 2; i < 100000; i++) {
    if (!Eratosthenes.at(i)) continue;
    for (int j = i * 2; j < 100000; j += i)
      Eratosthenes.at(j) = false;
  }
  for (int i = 2; i < 100000; i++) {
    if (!Eratosthenes.at(i)) continue;
    long long L = (long long)i * i;
    while (L <= N) {
      Ans += L;
      L *= i;
    }
  }
  cout << Ans << endl;
}