#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#define _GLIBCXX_DEBUG
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=1167167167167167167;
const int INF=2100000000;
const ll mod=998244353;
#define rep(i,a) for (ll i=0;i<a;i++)
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"YES\n"; else cout<<"NO\n";}


template<class T>
using square_matrix=std::vector<std::vector<T>>;
template<class T,T (*add_op)(T,T),T(*add_e)(),T (*mul_op)(T,T),T(*mul_e)()>
square_matrix<T> mul_matrix(square_matrix<T> l,square_matrix<T> r){
	int n=l.size();
	assert(l.size()==n&&l[0].size()==n&&r.size()==n&&r[0].size()==n);
	square_matrix<T> val(n,std::vector<T>(n,add_e()));
	for(int i=0;i<n;i++) for(int j=0;j<n;j++) for(int k=0;k<n;k++){
		val[i][k]=add_op(val[i][k],mul_op(l[i][j],r[j][k]));
	}
	return val;
}
template<class T,T (*add_op)(T,T),T(*add_e)(),T (*mul_op)(T,T),T(*mul_e)()>
square_matrix<T> pow_matrix(square_matrix<T> l,long long times){
	int n=l.size();
	square_matrix<T> val(n,std::vector<T>(n,add_e()));
	for(int i=0;i<n;i++) val[i][i]=mul_e();
	while(times){
		if(times&1){
			val=mul_matrix<T,add_op,add_e,mul_op,mul_e>(val,l);
		}
		l=mul_matrix<T,add_op,add_e,mul_op,mul_e>(l,l);
		times>>=1;
	}
	return val;
}

using mat_F=ll;
mat_F add_op(mat_F a,mat_F b){
	return (a+b)%mod;
}
mat_F add_e(){
	return 0;
}
mat_F mul_op(mat_F a,mat_F b){
	return (a*b)%mod;
}
mat_F mul_e(){
	return 1;
}
#define calc mat_F,add_op,add_e,mul_op,mul_e



void solve();

//  rainy ~ 雨に打たれて ~
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

	int t=1;
	//cin>>t;
	rep(i,t) solve();
}

void solve(){
	ll N;
	cin>>N;
	vector<int> p(N+1);
	vector<int> r(N+1);
	vector<bool> q(N+1,1);
	q[0]=0,q[1]=0;
	rep(i,N+1) r[i]=i;
	for(ll i=1;i<=N;i++){
		if(i*i>N) break;
		for(ll j=1+(N)/(i*i+2*i+1);j<=N/(i*i);j++) p[j]=i;
	}
	rep(i,N+1){
		if(!q[i]) continue;
		if(i*i>N) break;
		for(ll j=i*i;j<=N;j+=i*i) while(r[j]%(i*i)==0) r[j]/=(i*i);
	}
	ll ans=0;
	for(int i=1;i<=N;i++){
		//cout<<p[i]<<" "<<r[i]<<"\n";
		ans+=(ll)(p[r[i]]);
	}
	cout<<ans<<"\n";
}