..............................................................................................................................................1..........................................................................................................................1.........................................................................................................1.........................................................................................................3.............................................................................................8............................................................................................................................................18........................................................................................................................19............................................................................................................................................20........................................................................................................................21.......................................................................................................21.......................................................................................24...........................................................................................30...................................................................................................40.......................................................................................46...............................................................................................................48...............................................................................................48...............................................................................................48...............................................................................................51...............................................................................................57...............................................................................................59 .......................................................................................................64...............................................................................................................66........................................................................................................................................68 ₂ − − − − − − − −−− − −−− − −−−− − − − − − − − − − − − − − − ₂ − − − − − − − − ₂ −−− − − −−−₂ ₂ ⁻ −−−−− −−−−− −−−− ₂₄₂ ₂ − −− − − − − − − − ₂ ₂ 72