#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
using vi = vector<ll>;
using vvi = vector<vi>;
using vc = vector<char>;
using vvc = vector<vc>;
using vb = vector<bool>;
using vvb = vector<vb>;
using vs = vector<string>;
using pii = pair<ll, ll>;
using vpii = vector<pii>;
using vvpii = vector<vpii>;
using mint = modint998244353;
// using mint = modint1000000007;
#define endl '\n'
#define rep(i, a) for (ll i = 0; i < a; i++)
#define f(i, a, b) for (ll i = a; i < b; i++)
#define rf(i, a, b) for (ll i = a; i > b; i--)
#define all(x) (x).begin(), (x).end()
const ll INF = LLONG_MAX / 4;
vi dx = {1, 0, -1, 0, 1, 1, -1, -1};
vi dy = {0, 1, 0, -1, 1, -1, 1, -1};
void io_setup() {
    cin.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(16);
}

vector<bool> sieve_of_atkin(ll N) {
    vector<bool> isprime(N + 1);
    const ll sqrtN = sqrt(N);
    ll n;
    for (int z = 1; z <= 5; z += 4)
        for (int y = z; y <= sqrtN; y += 6) {
            for (int x = 1; x <= sqrtN && (n = 4 * x * x + y * y) <= N; ++x)
                isprime[n] = !isprime[n];
            for (int x = y + 1; x <= sqrtN && (n = 3 * x * x - y * y) <= N; x += 2)
                isprime[n] = !isprime[n];
        }
    for (int z = 2; z <= 4; z += 2)
        for (int y = z; y <= sqrtN; y += 6) {
            for (int x = 1; x <= sqrtN && (n = 3 * x * x + y * y) <= N; x += 2)
                isprime[n] = !isprime[n];
            for (int x = y + 1; x <= sqrtN && (n = 3 * x * x - y * y) <= N; x += 2)
                isprime[n] = !isprime[n];
        }
    for (int y = 3; y <= sqrtN; y += 6)
        for (int z = 1; z <= 2; ++z) {
            for (int x = z; x <= sqrtN && (n = 4 * x * x + y * y) <= N; x += 3)
                isprime[n] = !isprime[n];
        }
    for (int n = 5; n <= sqrtN; ++n)
        if (isprime[n])
            for (int k = n * n; k <= N; k += n * n)
                isprime[k] = false;
    isprime[2] = isprime[3] = true;
    return isprime;
}

vector<ll> primes(ll N) {  // これで素数のみをansに入れる
    auto isprime = sieve_of_atkin(N);
    vector<ll> ans;
    for (ll i = 2; i <= N; i++)
        if (isprime[i])
            ans.push_back(i);
    return ans;
}

int main(void) {
    io_setup();
    ll n;
    cin >> n;
    ll ans = 0;
    ll N = sqrt(n);
    vector<ll> p = primes(N);
    for(auto e : p){
        ll r = e*e;
        if(r > n)break;
        while(r <= n){
            ans += r;
            r *= e;
        }
        
    } 
    cout << ans << endl;
}