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

#include <atcoder/all>
using namespace atcoder;

using ll = long long;
using mint = modint998244353;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll N;
    cin >> N;
    ll ans = 0;
    const int L = 1 << 17;
    vector<bool> pr(L);
    for(ll p = 2; p * p <= N; p++) {
        if(pr[p]) continue;
        for(ll k = 1; k * p < L; k++) {
            pr[k * p] = true;
        }
        ll x = p;
        while(x <= N / p) {
            x *= p;
            ans += x;
        }
    }
    cout << ans << endl;
}