#include <fstream>
using namespace std;
int N,v[1000007];
long long R;
int main()
{
ifstream in("fractii.in");
in>>N;
in.close();
for(int i=1;i<=N;++i)
    {
        v[i]=i-1;
    }

for(int i=2;i<=N;i++)
    {
        for(int j=2;j*i<=N;++j)
            {
                v[i*j]-=v[i];
            }
    }

for(int i=2;i<=N;++i)
    {
        R+=v[i];
    }

R*=2;
R++;

ofstream out("fractii.out");
out<<R<<"\n";
out.close();
return 0;
}