The Fixed Period

! ! " # $ % & '( ) * + ,- , ( . . / . 0 . 12 3 453, 6662 &/ +/0 78 /9!/ 7 /! : &/ 1;/ / 1 666 ! " # $ $ ! % &' $ (&)$ * + %)+* ()!!) , -../ 0)+ + 1 /((/ = 111= &/ 1 2 ! / :3 >9= 1 7 93& ((= ;1= />/((@ ;11= 8 D ) * C . F * ) * B ** * D B = > ) F C B ) * B B 1 * C C ! C * C C C * B B . = 1 " 1 * . * . * . . C B C * C ) .