#!/usr/bin/env perl
use strict;
use warnings;
use feature 'say';

my @queue = '123456789';

while (@queue) {
        $_ = shift @queue;
        say if eval == 100;
        while ( /\d+?/g) {
                next if (!$' || $' =~ /\+|\-/);
                push @queue,("$`$&+$'","$`$&-$'");
        }
}