#!/usr/bin/perl
use strict;
use warnings;

$_ = '2 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2';
while (/(\d) (\d)/g) {
    my ($first, $second) = ($1, $2);
    # insert logic for output
}