/*
#pragma GCC target("avx")
#pragma GCC optimize("O2")
#pragma GCC optimize("inline")
#pragma GCC optimize("-ffast-math")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("no-stack-protector")
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define fo(i, a, b) for(ll i=a; i<=b; i++)
#define fod(i, a, b) for(ll i=a; i>=b; i--)
#define lop(x, s) for(auto x : s)
#define sz(s) s.size()
#define all(s) s.begin(), s.end()
#define pll pair<ll, ll>
#define pb push_back
#define mp make_pair
const ll maxn=5e7+5;

int n, f[7105];
ll res=0;
bool s[maxn];

void sang(){
    fo(i, 1, maxn){
        if(!s[i]){
            int j=2;
            while(f[j]*i<=maxn){
                s[f[j]*i]=1;
                j++;
            }
        }
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cin >> n;
    fo(i, 1, 7100){
        f[i]=i*i;
    }
    sang();
    fo(i, 1, n){
        if(!s[i]){
            ll a=sqrt(n/i);
            res+=f[a];
        }
    }
    cout << res;
    return 0;
}