process data(x y)

#!/usr/bin/perl
use strict;
use warnings;
use feature 'say';
sub dist {
  my ($x1, $y1, $x2, $y2) = @_;
  return sqrt(($x1 - $x2) * ($x1 - $x2) + ($y1 - $y2) * ($y1 - $y2));
}
my $data = [];
my $result = [];
while (<>) {
  chomp;
  my @d = split;
  push @$data, \@d;
}
my $size = scalar @$data;
for (my $i = 0; $i < $size; $i++) {
  for (my $j = $i + 1; $j < $size; $j++) {
    my $r = [$data->[$i][0], $data->[$i][1], $data->[$j][0], $data->[$j][1]];
    push @$r, dist @$r;
    push @$result, $r;
  }
}
@$result = sort { $a->[4] <=> $b->[4] } @$result;
foreach my $r (@$result) {
  say join "\t", @$r;
}