#include <fstream>

using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
long long n,i,j,x,v[1000005];
int main()
{
    cin>>n;
    for(i=1;i<=n;i++)
    {
        v[i]+=i-1;
        x+=2*v[i];
        for(j=2*i;j<=n;j+=i)
            v[j]-=v[i];
    }
    cout<<x+1;
    return 0;
}