#include<fstream.h>
#define nmax 1000000
int n,i,j,w[nmax+1]; long long nr;
int main()
{ifstream f("fractii.in"); ofstream g("fractii.out");
 f>>n; f.close();
 for(i=1;i<=n;i++)
  w[i]=i-1;
 for(i=2;i<=n/2;i++)
  for(j=2*i;j<=n;j+=i)
   w[j]=w[j]-w[i];
 nr=0;
 for(i=2;i<=n;i++)
  nr+=w[i];
 nr=1+2*nr;
 g<<nr<<'\n';
 g.close();
 return 0;
}