#!/usr/bin/perl

use strict;
use warnings;

my @PairLines;
my %Pairs;
my %PairsOf;

@PairLines = <DATA>;
chomp(@PairLines);

foreach my $Line (@PairLines) {
   chomp $Line;
   $Line   =~ s/^\s*//;
   $Line   =~ s/\s*$//;
   if ($Line =~ m/^Pairing Start (.*)\s+(.*).*/) {
      my $Person1  = $1;
      my $Person2  = $2;
      $Pairs{$Person1}  = $Person1 if (!defined($Pairs{$Person1}));
      $Pairs{$Person2}  = $Person2 if (!defined($Pairs{$Person2}));
      $PairsOf{$Person1}        = $PairsOf{$Person1} . " " . $Person2;
      $PairsOf{$Person2}        = $PairsOf{$Person2} . " " . $Person1;
   }
}


__DATA__
Pairing Start Person1 Person2
Pairing End
###########################################
Pairing Start Person1 Person3
Pairing End
###########################################
Pairing Start Person1 Person4
Pairing End
###########################################
Pairing Start Person1 Person5
Pairing End
###########################################
Pairing Start Person2 Person3
Pairing End