// #include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <string>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> PP;
// #define MOD 1000000007
#define MOD 998244353
#define INF 2305843009213693951ll
#define PI 3.141592653589
#define setdouble setprecision
#define REP(i,n) for(ll i=0;i<(n);++i)
#define OREP(i,n) for(ll i=1;i<=(n);++i)
#define RREP(i,n) for(ll i=(n)-1;i>=0;--i)
#define ORREP(i,n) for(ll i=(n);i>=1;--i)
#define rep(i,a,b) for(ll i=(a);i<=(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define chmin(k,m) k = min(k,m)
#define chmax(k,m) k = max(k,m)
#define GOODBYE do { cout << "-1" << endl; return 0; } while (false)
#define MM <<" "<<
#define Endl endl

std::vector<long long> primearray(long long N){
    // Copyright (c) 2023 0214sh7
    // https://github.com/0214sh7/library/
    std::vector<long long> R;
    std::vector<bool> prime;
    for(int i=0;i<=N;i++){
        prime.push_back(true);
    }
    if(N<2){
        return R;
    }
    prime[0]=false;
    prime[1]=false;
    for(long long i=2;i*i<=N;i++){
        if(!prime[i])continue;
        for(int j=2*i;j<=N;j+=i){
            prime[j]=false;
        }
    }
    for(long long i=0;i<prime.size();i++){
        if(prime[i]){
            R.push_back(i);
        }
    }
    return R;
}

int main(void){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    
    ll N;
    cin >> N;
    ll sN = 0;
    while((sN+1)*(sN+1)<=N)sN++;

    vector<ll> P = primearray(sN);
    ll Ans = 0;
    for(auto p:P){
        ll t = p*p;
        while(t<=N){
            Ans += t;
            t *= p;
        }
    }

    cout << Ans << endl;
    
    return 0;
    
}