#include <fstream>

using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int n,v[1000005];
long long rez;

int main()
{
    int i,j;
    fin>>n;
    fin.close();
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        rez+=v[i];
        for(j=i+i;j<=n;j+=i)
            v[j]-=v[i];
    }

    fout<<rez*2+1;
    fout.close();
    return 0;
}