#include<iostream>
#include<algorithm>
#include <vector>
#include<cmath>
#include<iomanip>
#include<queue>
using namespace std;
typedef long long int lint;
int main() {
	int N;
	cin >> N;
	int cnt = 0;
	int ans = 0;
	for (int ia = 2; ia <= N; ia++) {
		for (int ib = 1; ib <= N; ib++) {
			if (ia % ib == 0) {
				cnt++;
			}
		}
		if (cnt == 2) {
			ans += ia;
		}
		cnt = 0;
	}
	cout << ans << endl;
}