Thank you kyle, that helped a lot. Now, another problem has appeared.

I need to check for the presence of some values in the hash. For example, I am sure tha 1090 is in the hash. But the following code never evaluates as true and thus never does what's inside of the if statement.

for ($i=1;$i<5001;$i++){
if (exists $faclist{$i}){
print "$i\n";
}
}