var
   i,j,k,n:integer;
   f:text;
begin
     assign(f,'tije.in'); reset(f);
     Readln(f,n);
     close(f);
     assign(f,'tije.out'); rewrite(f);
     for i:=n-1 downto 1 do
     begin
          for j:=n downto 1 do
              for k:=1 to i do
                  writeln(f,j,' ',j+1);
          for j:=1 to i do
              writeln(f,n+1,' ',1);
     end;
     close(f);
end.