#include<iostream>
#include<string>
#include<vector>
#include<algorithm>
#include<cmath>
#include<stdio.h>
#include<queue>
#include <climits>
#include <map>
const int mod = 1e9 + 7;
const int INF = 1e9;
using namespace std;
typedef long long ll;

int main()
{
    int n;
    cin >> n;
    ll ans = 0;
    for(int i = 2; i <= n; i++){
        int cnt = 0;
        for(int j = 2; j <= i; j++){
            if(i % j == 0){
                cnt++;
            }
        }
        if(cnt == 1){
            ans += i;
        }
    }
    cout << ans << endl;
}