next until ($seed=~/[ACGTN-]/ && (!($seed =~ /\$seed/))) { 

# should be:
next unless ($seed=~/[ACGTN-]/ && (!($seed =~ /\$seed/))); 

##</code><code>##

(!($seed =~ /\$seed/))); 

##</code><code>##

$i=$i+1; 
}until($i>682);#Line 29