@s = qw(ABABC BABCA ABCBA);
sub l{length@_[0]};for$i(0..$#s){$l=l$s[$i];for$s(0..$l-1){for$o(1..$l-$s)
{$t=substr$s[$i],$s,$o;if(!$i||exists$c{$t}){$c{$t}|=1<<$i}}}};print join$/,
'Common subsequences:',@s,'-'x30,sort{l($b)<=>l$a}grep{$c{$_}==(1<<@s)-1}keys%c;