#include <algorithm>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>

using namespace std;

typedef long long ll;

#define MOD 1000000007

int main() {
  int n;
  cin >> n;
  vector<bool> p(1001, true);
  for (int i = 2; i <= 1000; ++i) {
    if (p[i]) {
      for (int j = 2; i * j <= 1000; ++j) {
        p[i * j] = false;
      }
    }
  }
  ll ans = 0;
  for (int i = 2; i <= n; ++i) {
    if (p[i]) ans += i;
  }
  cout << ans << endl;
  return 0;
}