#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define Pr pair<ll,ll>
#define Tp tuple<ll,ll,ll>
using Graph = vector<vector<Pr>>;

ll mod = 998244353;

int main() {
    ll N; cin >> N;
    ll nsf[N+1];
    rep(i,N+1){
        nsf[i] = i;
    }
    for(ll i=1;i<=N;i++){
        if(nsf[i]==i){
            rep(j,N){
                if(i*j*j>N) break;
                nsf[i*j*j] = i;
            }
        }
    }
    ll counter[N+1];
    ll k = N;
    rep(i,N+1){
        while((ll)i*k*k>N) k--;
        counter[i] = k;
    }
    ll ans = 0;
    rep(i,N){
        ans += counter[nsf[i+1]];
    }
    cout << ans << endl;
}