for my $key (  sort{ local $^W; $a <=> $b } keys %h ) {

    last if do{ local $^W; 0 + $key } >= 20;
    print "$key : $h{ $key }";
};;

0 YLJG : just a placeholder
1 ERHC : just a placeholder
2 UEGHWMGJVWDAUEOJR : just a placeholder
3 TPFZPXPS : just a placeholder
3 VDII : just a placeholder
4 SHHSRQLJVXTOPBYXT : just a placeholder
4 RXWZUUDA : just a placeholder
7 IPSCGIHLBWPR : just a placeholder
9 JRPAZKPXSC : just a placeholder
10 BGE : just a placeholder
11 OI : just a placeholder
11 HYXKTCLHDWCO : just a placeholder
14 QU : just a placeholder
16 ASJOWMLOWWMJWHDRAZ : just a placeholder
17 SQUJMOIM : just a placeholder
18 PFZDZODFMLBCVLTXQF : just a placeholder
18 AYYUCHEUXMNTTVLTJB : just a placeholder
19 KBDNXHCLUHEXSM : just a placeholder