#!perl -w
use strict;

my $tokens = "32,15,4,72,13,28,14";

my %ranking = do { my $i; map { $_ => $i++ } split /,/, $tokens };
my ($default) = ($tokens =~ m/,(\d+)$/); # last token

while (my $list = <DATA>) {
  chomp $list;
  my $best = $default;
  for my $b (split /,/, $list) {
    next unless defined $ranking{$b};
    $best = $b if $ranking{$b} < $ranking{$best};
  }
  print "$best\n";
}

__DATA__
4,13,15
4,50,15,13
50,60,70

##</code><code>##

#!perl -w
use strict;

my $tokens = "32,15,4,72,13,28,14";

my @ranking = split (/,/, $tokens);
my $default = $ranking[$#ranking]; # last token

while (my $list = <DATA>) {
  chomp $list;
  my %list = map {$_ => 1} split /,/, $list;
  my $best = ( grep {$list{$_}} @ranking )[0] || $default;
  print "$best\n";
}

__DATA__
4,13,15
4,50,15,13
50,60,70