#include <bits/stdc++.h>
#include <atcoder/all>
#include <iostream>
#include <cmath>
using namespace std;
using namespace atcoder;
using ll = long long;
using P = pair<ll, ll>;
using Graph = vector<vector<ll>>;
using WGraph = vector<vector<pair<ll, ll>>>;
using mint = modint998244353;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
mt19937_64 rng(58);
long double PI = 3.14159265358979;
const ll LLMAX = 9223372036854775807;
const ll INF = 1e18;
vector<ll> di = {1, 0, -1, 0};
vector<ll> dj = {0, -1, 0, 1};
void chmin(ll& x, ll y) { x = min(x, y);};
void chmax(ll& x, ll y) { x = max(x, y);};

int main() {
    ll n;
    cin >> n;

    const ll M = 1e5 + 100;
    ll ans = 0;
    vector<bool> isPrime(M, true);
    isPrime[0] = false;
    isPrime[1] = false; 
    for (ll i = 1; i < M; i++) { 
        if (isPrime[i]) {
            for (ll j = i + i; j < M; j += i) {
                isPrime[j] = false;
            }
            ll num = i * i;
            while (num <= n) {
                ans += num;
                num *= i;
            }
        }
    }

    cout << ans << endl;
    return 0;
}