#include <bits/stdc++.h>
#define rep(i,n)for(long long i=0;i<(n);i++)
using namespace std;
typedef unsigned long long ull;
typedef long long ll;
const ll INF=1e18;
const int MOD=1e9+7;
const double pi=acos(-1);
bool is_prime(long long n) {
    if (n <= 1) return false;
    for (long long p = 2; p * p <= n; ++p) {
        if (n % p == 0) return false;
    }
    return true;
}
int main(){
  int n;
  cin >> n;
  ll ans=0;
  rep(i,n){
    if(is_prime(i+1))ans+=i+1;
  }
  cout << ans << endl;
}