.
( ), 3 :
1- -.
2- .
3-- .
-----------------------------------------------
. :
-6-.
20 (18- + 2 ).
.
1 -,*3 , 4 , 3 *.
2 - .
3 -,*3 , ( 4- )- - , , -- , - , - . , 4 - . 3 *.
.
4 - .
1-4 .
..- . , .
-----------------------------------------------------------------------
, (6 )- .
--------------------------------------------------------------------------------
, . .