hi , I want to create directory with input but ıt create random name?

#!/use/perl/bin
use strict;
print "Enter directory name :";
my $directory_name = <STDIN>;
my $dir = "C:\Users\darkblack\Desktop\A\.$directory_name"; 
# It is proble , I cant write true format in up line
mkdir( $dir ,0755) or die "Couldn't create $dir directory, $!";
print "Directory created successfully\n";
[download]

Created folder name is SERSDARKBLACKDESKTOPA$DIRECTORY_NAME