#include <fstream>
#include <string>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long long n,i,j,s,v[1000010];
int main()
{
    f>>n;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=i*2;j<=n;j+=i)
            v[j]-=v[i];
        s+=v[i];
    }
    g<<s*2+1<<'\n';
    return 0;
}