#!/usr/bin/perl --
use strict; use warnings;
my @x = ('a' .. 'z');
print yup( 5, @x ),"\n--\n";
print yup( 3, @x ),"\n";
sub yup {
    my( $n, @x ) = @_;
    my @yo;
    for( my $ix = 0; $ix < @x; $ix += $n )
    {
        my $high = $n - 1 + $ix ;
        $high > $#x and $high = $#x ;
        push @yo, join ' ', @x[ $ix .. $high ];
    }
    return join ",\n", @yo;
}
__END__
a b c d e,
f g h i j,
k l m n o,
p q r s t,
u v w x y,
z
--
a b c,
d e f,
g h i,
j k l,
m n o,
p q r,
s t u,
v w x,
y z