var f:text;
    a:array [1..1000000] of longint;
    n:longint;
    s:int64;
procedure element;
  var i,j:longint;
  begin
    for i:=2 to n do a[i]:=i-1;
    for i:=1 to n div 2 do begin
                             j:=2*i;
                             while j<=n do begin
                                             a[j]:=a[j]-a[i];
                                             j:=j+i;
                                           end;
                           end;
    for i:=2 to n do s:=s+a[i];
    s:=s*2+1;
  end;
begin
  assign(f,'fractii.in');
  reset(f);
  read(f,n);
  close(f);
  element;
  assign(f,'fractii.out');
  rewrite(f);
  write(f,s);
  close(f);
end.