var  n,i,k,aux:longint;
     rs:qword;
     a:array[1..1000001] of longint;
begin
assign(input,'fractii.in');
assign(output,'fractii.out');
reset(input);
rewrite(output);
 readln(n);

  for i:=2 to n do
   a[i]:=i*2-2;

    for i:=2 to (n div 2)+1 do
      begin
       aux:=2*i;
        while aux<=n do
         begin
          dec(a[aux],a[i]);
          inc(aux,i);
         end;
      end;

    for i:=1 to n do
     inc(rs,a[i]);
      writeln(rs+1);



close(input);
close(output);
{Totusi este trist in lume}
end.