#include <bits/stdc++.h>

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
const int N = 2000086, MOD = 998244353, INF = 0x3f3f3f3f;
int n, m, w[N];


char s[N];

int primes[N], cnt;
bool st[N];
inline void init() {
    for (int i = 2; i < N; i++) {
        if (!st[i]) primes[cnt++] = i;
        for (int j = 0; primes[j] * (ll)i < N; j++) {
            st[i * primes[j]] = 1;
            if (i % primes[j] == 0) break;
        }
    }
}

int main() {
    init();
    ll n, res = 0;
    cin >> n;
    for (int i = 0; (ll)primes[i] * primes[i] <= n; i++)
        for (ll j = (ll)primes[i] * primes[i]; j <= n; j *= primes[i])
            res += j;
    printf("%lld\n", res);
    return 0;
}