#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<stack>
#include<algorithm>
#include<cmath>
#include<climits>
#include<string>
#include<set>
#include<numeric>
#include<map>
#include<iostream>
using namespace std;
#define rep(i,n) for(int i = 0;i<((int)(n));i++)
#define reg(i,a,b) for(int i = ((int)(a));i<=((int)(b));i++)
#define irep(i,n) for(int i = ((int)(n)-1);i>=0;i--)
#define ireg(i,a,b) for(int i = ((int)(b));i>=((int)(a));i--)
typedef long long ll;
typedef pair<ll, ll> mp;
ll mod = 1e9+7;
ll inf = 1e18;

//WA

int main(void){
	ll n,a[1010]={},sum=0;
	reg(i,2,1000){
		if(a[i]==0){
			reg(j,2,1000){
				if(i*j>1000)break;
				a[i*j]=1;
			}
		}
	}
	cin>>n;
	reg(i,2,n){
		if(a[i]==0)sum+=i;
	}
	cout<<sum<<endl;
	return 0;
}