Error(s):

(15:26) The name 'lastX' does not exist in the current context
(16:26) The name 'y' does not exist in the current context
(17:30) The name 'x' does not exist in the current context
(20:21) The name 'y' does not exist in the current context
(20:33) The name 'x' does not exist in the current context
(22:21) The name 'x' does not exist in the current context
(22:37) The name 'y' does not exist in the current context
(25:26) The name 'y' does not exist in the current context
(25:38) The name 'x' does not exist in the current context
(27:21) The name 'x' does not exist in the current context
(27:37) The name 'x' does not exist in the current context
(32:20) The name 'x' does not exist in the current context