#include <bits/stdc++.h>
using namespace std;
#define REP(i,a,n) for(int i=(a); i<(int)(n); i++)
#define rep(i,n) REP(i,0,n)
#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it)
#define ALLOF(c) (c).begin(), (c).end()
typedef long long ll;
typedef unsigned long long ull;

#define PMAX 1000000
bool isprime[PMAX+1];
void init_prime(){
fill(isprime, isprime+PMAX+1, true);
isprime[0] = isprime[1] = false;
for(int i=2; i<=PMAX; i++) {
if(!isprime[i]) continue;
for(int j=i*2; j<=PMAX; j+=i){
isprime[j] = false;
}
}
}

int main(){
  init_prime();
  int N;
  cin >> N;
  int ret = 0;
  REP(i,2,N+1){
    if(isprime[i]) ret+=i;
  }
  cout << ret << endl;
  return 0;
}