use strict;
my $str = '
<a href="https://cloud.saikoanimes.net/11Yu" class="btn-sa" target="blank">01</a>
<a href="https://cloud.saikoanimes.net/BXz" class="btn-sa" target="blank">02</a>
<a href="https://cloud.saikoanimes.net/BXv" class="btn-sa" target="blank">03</a>
<a href="https://cloud.saikoanimes.net/11Yx" class="btn-sa" target="blank">04</a>
<a href="https://cloud.saikoanimes.net/BXt" class="btn-sa" target="blank">05</a>
<a href="https://cloud.saikoanimes.net/BXw" class="btn-sa" target="blank">06</a>
<a href="https://cloud.saikoanimes.net/11Yv" class="btn-sa" target="blank">07</a>
<a href="https://cloud.saikoanimes.net/BXx" class="btn-sa" target="blank">08</a>
<a href="https://cloud.saikoanimes.net/BXy" class="btn-sa" target="blank">09</a>
<a href="https://cloud.saikoanimes.net/11Yo" class="btn-sa" target="blank">10</a>
<a href="https://cloud.saikoanimes.net/11Ym" class="btn-sa" target="blank">11</a>
<a href="https://cloud.saikoanimes.net/11Yw" class="btn-sa final" target="blank">12</a> ';
my $regex = qr/.*(https:\/\/cloud\.saikoanimes\.net\/.*)" c.*/mp;
my $subst = '$1';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html