#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct io_setup {
	io_setup() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} io_setup;

using mint = atcoder::modint998244353;

namespace cho {

std::vector<int> prime_table(int n) {
	std::vector<int> p(n + 1, -1);
	for (int i = 2; i * i <= n; i++) {
		if (p[i] != -1) continue;
		for (int j = i * i; j <= n; j += i) {
			p[j] = i;
		}
	}
	return p;
}

std::vector<int> prime_list(int n) {
	std::vector<int> res;
	auto p = prime_table(n);
	for (int i = 2; i <= n; i++) {
		if (p[i] == -1) res.push_back(i);
	}
	return res;
}

}  // namespace cho

// isqrt
long long isqrt(long long n) {
	if (n <= 0) return 0;
	long long x = sqrt(n);
	while ((x + 1) * (x + 1) <= n) x++;
	while (x * x > n) x--;
	return x;
}

void solve() {
	ll n;
	cin >> n;
	auto v = cho::prime_list(isqrt(n));
	ll ans = 0;
	for (auto p : v) {
		ll res = (ll)p * p;
		while (res <= n) {
			ans += res;
			res *= p;
		}
	}
	cout << ans << '\n';
}

int main() {
	int t = 1;
	// cin >> t;
	while (t--) solve();
}