use Math::BigInt;
use List::Util;

my $a = Math::BigInt->new ('1000000000000000000000000000000000000000000');
my $b = Math::BigInt->new ('1000000000000000000000000000000000000000000');

my $c = List::Util::sum ($a, $b);
print "$c\n";
print ref $c;