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

using ll = int64_t;

ll N;

void input() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cin >> N;
}

inline ll isqrt(ll n) {
    if (n < 0) return -1;
    if (n == 0) return 0;
    ll sq = sqrt(n) - 1;
    return sq * (sq + 2) < n ? sq + 1 : sq;
}

vector<bool> P;

void sieve(ll n) {
    ll sq = isqrt(n);
    P.assign(sq+1, true);
    for (ll i=2; i<=sq; ++i) {
        if (!P[i]) continue;
        for (ll j=i*i; j<=sq; j+=i) P[j] = false;
    }
}

void solve() {
    sieve(N);
    ll l = P.size();
    ll ans = 0;
    for (ll i=2; i<l; ++i) {
        if (!P[i]) continue;
        for (ll j=i*i; j<=N; j*=i) ans += j;
    }
    cout << ans << "\n";
}

int main() {
    input();
    solve();
    return 0;
}