#include<bits/stdc++.h>

#define all(s) s.begin(),s.end()
#define rc(x) return cout<<x<<endl,0
#define forn(i,n) for(int i=0;i<int(n);i++)
#define len(a) (int) (a).size()

#define pb push_back
#define mp make_pair
#define fr first
#define sc second

typedef long long ll;
typedef long double ld;

const int nmax=2e5+3;
const int mod=998244353;
const ll inf=0x3f3f3f3f3f3f3f3f;

/*===================*\
      comentarii:
\*===================*/

using namespace std;


int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    int n;
    ll sol=0;
    cin>>n;
    int v[n+3];
    for(int i=1;i<n;i++)
        v[i+1]=i;
    for(int i=2;i<=n;i++)
    {
        sol+=v[i];
        for(int j=i*2;j<=n;j+=i)
            v[j]-=v[i];
    }
    cout<<sol*2+1;
}