package Stack;
use strict;

sub new {
  my $class = shift;
  my $self = {};
  $self->{stack} = [];
  $self->{top} = -1;
  bless $self, $class;
}
sub push {
  my $self = shift;
  my $i = shift;
  if ($self->{top} < 1000 - 1) {
    $self->{stack}->[++$self->{top}] = $i;
  }
}
sub pop {
  my $self = shift;
  if ($self->{top} != -1) {
    return $self->{stack}->[$self->{top}--];
  }
  return -99999;
}
1;