#include <fstream>
using namespace std;
ifstream fi ("fractii.in");
ofstream fo ("fractii.out");
long long sol;
int rez[1000003], n,i,j;
int main ()
{
    fi>>n;
    for( i=1;i<=n;i++)
        rez[i]=i-1;
    for( i=2;i<=n;i++)
    {
        for(j=2*i;j<=n;j+=i)
            rez[j]-=rez[i];
        sol=(long long)sol+rez[i];
    }
    fo<<2*sol+1;
    return 0;
}