Which keyboard key should the user press to print out "CORRECT BUTTON PRESSED" when the program below is executed?

$.$ORIG x$3000$

BEGIN GETC

BRzp METHOD

ADD R$2,$ R$2,$ #$1$

METHOD LD R$1,$ VALUE

ADD R$1,$ R$0,$ R$1$

BRz SUCCESS

BRnp EXIT

SUCCESS LEA R$0,$ CORRECT

PUTS

EXIT HALT

VALUE $.$FILL #FFC$0$

CORRECT $.$STRINGZ $$CORRECT BUTTON PRESSED$$

$.$END