my @menu = ( "Go left", "Go right" );

  for my $i ( 0 .. $#menu ) { print $i+1, ") $menu[$i]\n"; }

  print "?";
  $_ = <>;
  ($_) = /^(\d+)/; # extract just the digits, if any.
  $_--; # because the menu as displayed in 1-based.

  # now do whatever you want with the number in $_ and
  # the full text of the selected menu item in $menu[$_].