#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <utility>
#include <queue>
#include <stack>
#include <cmath>
#include <numeric>

#define rep(i,j,k) for(int i=(int)j;i<(int)k;i++)
#define ll long long
using namespace std;
int day[12]={31,28,31,30,31,30,31,31,30,31,30,31};

bool isPrime(int x){
    if(x==1)return 0;
    else if(x==2)return 1;
    else if(x%2==0)return 0;

    for(int i=3;i*i<=x;i++)if(x%i==0)return 0;
    return 1;
}
int main(){
    int n;
    cin>>n;
    int ans=0;
    rep(i,1,n+1){
        if(isPrime(i))ans+=i;
    }
    cout<<ans<<endl;
}