#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#include<vector>
using namespace std;
typedef long long ll;
#define rep(i,s,n)for(int i = s;i<n;i++)
#define repe(i,s,n)for(int i = s;i<=n;i++)
static const ll maxLL = (ll)1 << 62;

int main(){
   int n,sum=0;
   cin>>n;
   
   bool can=true;
   rep(i,2,n+1){
       can=true;
       rep(j,2,i){
           if(i%j==0)can=false;
       }
       if(can)sum+=i;
   }
   cout<<sum<<endl;
   return 0;
}