#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = a; i < b; i++)
using ll = long long;

int main(){
	ll n;
	cin >> n;
	double sq = sqrt(n);
	int r = ceil(sq);
	vector<int> v(r + 1, 1);
	v[0] = 0;
	v[1] = 0;
	rep(i, 2, r + 1) {
		if(v[i] == 0) continue;
		for(int j = i + i; j < r + 1; j += i) v[j] = 0;
	}
	vector<int> p;
	rep(i, 2, r + 1) if(v[i]) p.push_back(i);
	ll ans = 0;
	for(ll e : p) {
		ll f = e * e;
		while(f <= n) {
			ans += f;
			f *= e;
		}
	}
	cout << ans << endl;
}