% perl -e 'print join(" ",map $_->[0]x$_->[1], (["a",64],["b",64],["c",65],["d",65]))' | 
  perl -e '$_=<STDIN>; foreach(split){print "$_\n"}'

=head1 OUTPUT
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
ddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd