.
500 . , , 50 -100 . , ( ), 5-6 3 4 5-6-7 1 5-6 3-4 . , . , 30-35 . , . , , , . . , , 1/4 , . . , : , ( ) 2 . 1/2 ( ) 1/2 1/2 ( , ) 1/2 ( , ) 1/2 ( ) 1/2 1/2 ( ) . . , 2 . , ... .
1.