#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, e) for (int i = (int)(s); i < (int)(e); ++i)

int main() {
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	
	int maxi = 100100;
	vector<bool> isprime(maxi, true);
	isprime[0] = isprime[1] = false;
	
	rep(i, 0, maxi) if (isprime[i]) {
		for (int j = i*2; j < maxi; j += i) isprime[j] = false;
	}
	
	ll N;
	cin >> N;
	
	ll ans = 0;
	rep(i, 0, maxi) if (isprime[i]) {
		ll t = (ll)i * (ll)i;
		while (t <= N) {
			ans += t;
			t *= i;
		}
	}
	cout << ans << '\n';
}