in reply to quiting program

You'll need to setup a signal handler to catch the ctrl-c.
my $num_ctrlc = 0; $SIG{'INT'} = sub { $num_ctrlc++; print "Got $num_ctrlc ctrl-c\n"; exit if $num_ctrlc > 2; }; # rest of program
The $SIG{'INT'} part creates a signal handler for 'interrupt' (control-c) with your code. In this case, a little sub that increments a global counter, prints a message, and exists if the counter is above a certain number

BTW, your while loop is only going to run once, since @a will contain ALL of STDIN on the first pass... Perhaps you meant something more like:

while ($a = <STDIN>) { print $a; }

OmG! They killed tilly! You *bleep*!!