$diss = "\\bleen\\";
mkdir $diss,0777 or die "can't make dir: $!";

$diss = "\\bleen\\";
mkdir "$diss",0777 or die "can't make dir: $!";

$diss = "\\bleen\\";
mkdir ($diss,0777) or die "can't make dir: $!";

$diss = "\\bleen\\";
mkdir ("$diss",0777) or die "can't make dir: $!";