use strict;
use warnings;

my %allNames;
while (<DATA>) {
  chomp;
  $allNames{$_} = 1; 
}

for my $testName ("John Lennon", "Raubtier", "Paule McC") {
  print "$testName ist " . ($allNames{$testName} ? "" : "nicht ") . "drin\n";
}
__DATA__
John Lennon
Paule McC