#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
using ll = long long;
#define rep(i, n) for (int i = 0; i < (n); ++i)

int main() {
  constexpr auto is_prime = [] {
    array<bool, 1001> res {};
    res[0] = res[1] = false;
    for (int i = 2; i <= 1000; ++i) {
      res[i] = true;
      for (int j = 2; j * j <= i; ++j) {
        if (i % j == 0) {
          res[i] = false;
        }
      }
    }
    return res;
  }();
  int n;
  cin >> n;
  int ans = 0;
  rep(i, n + 1) if (is_prime[i]) ans += i;
  cout << ans << endl;
  return 0;
}