#!/usr/bin/perl

my @set = map {[split /\s+/]} <DATA>;

# We want for each number a list of which sets it's in:
for (@set) {
  for (@$_) {
    push @{$sets{$_}}, $setnum+0; # +0 numifies undef.
  } $setnum++
}

my ($element, $k) = (1, 3); # or =@ARGV or whatever.
{ my %count;
  # Note that this block could be a loop with different
  # values of $element and $k each time.

  for (@{$sets{$element}}) {
    for (uniq(grep { $_ != $element } @{$set[$_]})) {
      $count{$_}++; }
  }

  my @result = (sort { $count{$b} <=> $count{$a} } keys %count)[0..($k-1)];

  print "Results:  ", (join ", ", map {"($element, $_)"} @result), $/;
}

sub uniq {
  my %used;
  return grep { !$used{$_}++ } @_
}

__DATA__
2 4 5 7 8 10
1 2 5 6 7 9
2 6 7 8 9 10
1 3 5 10
1 3 4 5 6 8 9
1 2 4 6
1 2 4 5 7 10
1 3 4 6 7 8 9



##</code><code>##

$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}}
split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/