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for('00'..'99'){$x{$_}++unless $x{reverse()}};print keys%x;
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for$a(0..9){for(0..9){$x.="$a$_"if$_>=$a}}print$x;
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$_=9;for$a(0..9){for$b($a..9){$_.="$a$b"}s/$a{3}/$a$a/}print
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$_=9;for$a(0..9){for$b($a..9){$_.="$a$b"}s/$a$a/$a/}print