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.