#include<bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
    ll n;
    cin>>n;
    vector<ll> cnt(n+2,0);
    for(ll i = 1;i*i<=n;i++){
        ll le = n / (i*i);
        cnt[1]++;
        cnt[le+1]--;
    }
    for(int i = 1;i<=n+1;i++) cnt[i] += cnt[i-1];
    for(ll i = 2;i*i<=n;i++){
        ll now = i * i;
        for(;now<=n+1;now+=i*i) cnt[now] = 0;
    }
    ll ans = 0;
    for(int i = 1;i<=n;i++) ans += cnt[i] * cnt[i];
    cout<<ans<<endl;
}