$_=<>;{">+"=>sub{print"Hello, world!"},"++"=>sub{s/(\+*)\./print chr length$1/eg},">>"=>sub{$_="18/b
18b/b
16/b3
16b/b
14/b b/
16b
12/4
12b/b
10/2b/
10b/b
9b2/
8b/b
6/b3
7/b
4/b2/
5/ 
3b b/
4b
/b3
b b
 b/";s/b/\\/g;s/\d+/$"x$&/eg;print}}->{substr$_,0,2}()