#include <bits/stdc++.h>
using namespace std;
int main () {
	using ll = long long;
	ll N;
	cin >> N;
	std::vector<int> sosu(100010, 1);
	sosu[0] = sosu[1] = 0;
	ll ans = 0;
	for (ll i = 2; i * i <= N; i ++) {
		if (sosu[i]) {
			for (ll j = i * 2; j < 100010; j += i) {
				sosu[j] = 0;
			}
			ll x = i * i;
			while (x <= N) {
				ans += x;
				x *= i;
			}
		}
	}
	cout << ans << endl;
}