#include<bits/stdc++.h>
typedef long long ll;
#define REP(i,n) for(int i = 0;i < (n);i++)
#define rep(i,m,n) for(int i = (m);i < (n);i++)
#define P pair<int,int>
#define pb push_back
#define mk make_pair
using namespace std;
#define Vec(a) vector <int> a
const int INF = 1 << 20;
const int MOD = 1e9+7;

bool Sosuu(int r){
  for(int i = 2;i <= sqrt(r);i++){
    if(r%i == 0)
      return false;
  }
  return true;
}



int main(){
  int n;
  cin >> n;
  ll cnt = 0;
  rep(i,2,n+1){
      bool f = Sosuu(i);
      if(f){
          cnt += i;
      }
  }
  cout << cnt << endl;
  return 0;
}