#include<fstream>
int v[1000005];
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int main()
{

int i,j;

long long a,b;

f>>a;
b=0;


 for(i=1;i<=a;i++)
   v[i]=i-1;
        for(i=2;i<=a;i++)
            for(j=i+i;j<=a;j+=i)
                v[j]-=v[i];
                for(i=1;i<=a;i++)
                    b+=v[i];

b=b*2+1;
g<<b;
return 0;
}