#!/usr/bin/perl -w
use strict;

my @diseases = ();

$diseases[0] = ['flu','cold'];
$diseases[1] = ['Diabetics'];
$diseases[2] = ['Typhoid'];
$diseases[3] = ['Measels'];

for(my $priority = 0;$priority < scalar(@diseases);$priority++){
    print "Priority $priority diseases:\n";
    foreach(@{$diseases[$priority]}){
        print "\t$_\n";
    }
}