my %frequencies;
my $overlap;
foreach my $upper (@ranges) {
    if (defined $overlap) { 
     	next unless $overlap <= $upper;
     	$frequencies{$upper} ++; # $overlap is within the range
    }
    while (<$IN_FILE>) {
          chomp;
          if ($_ <= $upper) {
               $frequencies{$upper} ++;
          } else {
               $overlap = $_;
               last;
          }
    }
}