#include<fstream>
using namespace std;
ifstream f("fractii.in");ofstream g("fractii.out");
int n,v[1000000],i,j;
long long c;
int main()
{	f>>n;
    for(i=2;i<=n;i++)
    v[i]=i-1;
    for(i=2;i<=n;i++)
        {for(j=2*i;j<=n;j=j+i)
       v[j]=v[j]-v[i];}
       for(i=2;i<=n;i++)
       c=c+v[i];
    g<<c*2+1;g.close();
    return 0;
}