while (<>) {
next if $_ =~ m/\n{1}/;
if ($_ =~ m/\n{2}){s/\n{2}/\n/gs}
elsif ($_ =~ m/\n{3,}){s/\n{3,}/\n\s/gs}
}

##</code><code>##

while (<>) {
     if ($_ =~ m/\n{1}/) {
     }
     if ($_ =~ m/\n{2}/){
          s/\n{2}/\n/gs;
          print;
     }
     elsif ($_ =~ m/\n{3,}/){
          s/\n{3,}/\n/gs;
          print;
     }
}

##</code><code>##

while (<>) {
     if ($_ =~ m/\S\n{2}\S/){
          s/(\S)\n{2}(\S)/$1\n$2/gs;
          print;
     }
     elsif ($_ =~ m/\n{3,}/){
          s/\n{3,}/\n\n/gs;
          print;
     }
}