Fib Tangled

#!/usr/bin/perl -w

use strict;

my $num = shift @ARGV || die;

die "Not a number: $num\n" if $num !~ /^\d+$/;

print "Fib($num) = ", &fib($num), "\n";

sub fib {
    my $n = shift;

    if ($n <= 2) {
        return 1;
    } else {
        return 
&fib($n-2) + &fib($n-1);

    }
}