Main function

$###########v######################################

>..9n_3n{5Av# 'H' = 9*8 # 'w' = (2*8-1)*8-1 #

#vA3_[_A7_A<# 'e' = 'H'+3*8+5 # 'o' = 'W'-8 #

#>_[5n{4A_[v# 'l' = 'e'+7 # 'r' = 'o'+3 #

#vS1{n2[_n4<# 'l' # 'l' = 'r'-6 #

#>n{1S_8S_3v# 'o' = 'l'+3 # 'd' = 'l'-8 #

#v[_S8_S6_A<# ',' = 5*8+ 4 # '!' = 4*8+1 #

#>4n{1A_[..!# ' ' = 4*8 # <

$###########^######################################

Multiply by 8 (Bidirectional)

n####v#####

>{8}m#m}8{<

n####^#####

Push on left stack and print (Bidirectional)

_##v###

>{!#!{<

_##^###

Add (Bidirectional)

A##v###

>}a#a}<

A##^###

Subtract (Bidirectional)

S##v###

>}s#s}<

S##^###