#include <fstream>
#define MAX 1000000
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int v[1000005];
int main()
{
    long long s=0;
    int i,j,n;
    in >>n;
        v[1] = 1;
    for(i=2; i<=n; i++)
    {
        v[i]=i-1;
    }
    for(i=2; i<=n; i++)
    {
        s=s+v[i];
        for(j=2*i; j<=n; j+=i)
        {
            v[j]=v[j]-v[i];
        }
    }
    out<<s*2+1;
    return 0;
}