#!/usr/bin/perl -l

# https://perlmonks.org/?node_id=11100080

use strict;
use warnings;
use List::Util qw( sum );

my @A = (1, 1, 1, 1);
my @B = (2, 2, 2, 2);

print sum map eval tr/x/*/r, glob join 'x', map "{$A[$_],$B[$_]}", 0 .. $#A;