Here's my guess at something like what you want. Instead of printing @match and @nomatch at the end, just write their contents to the proper files, and change the input to read from your input file.

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11109150
use warnings;

my $x = 9;

my %uniques;
my @match;
my @nomatch;

while( <DATA> )
  {
  print;
  for my $element ( split )
    {
    if( keys %uniques < $x )
      {
      $uniques{ $element }++;
      }
    else
      {
      if( $uniques{ $element } )
        {
        push @match, $element;
        }
      else
        {
        push @nomatch, $element;
        }
      }
    }
  }

print "\nMATCH:\n@match\n\nNOMATCH:\n@nomatch\n";

__DATA__
1 2 6 4 5
6 7 8 9 10
1 2 11 12 13
6 14 15 16 17
[download]

Outputs:

1 2 6 4 5
6 7 8 9 10
1 2 11 12 13
6 14 15 16 17

MATCH:
1 2 6

NOMATCH:
11 12 13 14 15 16 17
[download]