Must be placed in a file to work, and the first line of the file must be the "sub v...". No #!perl allowed.

sub v{die} $/='a0';
pipe STDIN=>STDERR;
fork&&&a(a)||fork&&&v||fork&&&a||fork&&&O(0)||
fork&&&e||fork&&&a||fork&&&a($/);sub a{die @_}
sub O{die @_}
$_=<>;s/(([^D].?) )?.*(.).
/$2$3/g;print pack'h*',$_;
sub e{die}
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