my @files = <substituent_R*.txt>;

##</code><code>##

use Data::Dumper;
$Data::Dumper::Useqq = 1;
warn(Dumper(\@files));

##</code><code>##

my $avg = $sum / $cnt;

##</code><code>##

warn("Average=$avg\n");

##</code><code>##

warn(__LINE__, " for $fn_in\n");