#include<fstream>
using namespace std;
int phi[1000001],n,i,j;
long long suma=0;
int main()
{
    fstream fin("fractii.in",ios::in);
    fstream fout("fractii.out",ios::out);
    fin>>n;
    for(i=1;i<=n;++i) phi[i]=i-1;
    for(i=1;i<=n;++i)
      for(j=2*i;j<=n;j+=i) phi[j]-=phi[i];
    for(i=2;i<=n;++i) suma+=phi[i];
    fout<<1+2*suma;
    return 0;
}