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

my @data;

while (<DATA>)
{
	while (/(\d+\.\.\d+)/g)
	{
		push @data, $1;
	}
}

print "@data\n";

__DATA__
This is a file that contains lines like this
12..13 13..14 14..15 15..1 15..2 14..3 13..16 
that we want to extract.
16..4 16..17 17..5 17..18 18..6 18..7 12..19 19..20 20..8 20..10 19..9 12..11
That was another one