0 = (આર / 2 - 1) (આર / 2 - 2) x આર / 2-3 - (1/2) (r / 2 - 1) x r / 2-2 + ( 1/4 ) x r / 2-1 - ( 1/2 ) ( r / 2 - 1) x r / 2-2