@1
MOV 999 ACC
L:SAV
MOV UP DOWN
SUB DOWN
JGZ N
MOV DOWN NIL
SWP
C:MOV -4 DOWN
JMP L
N:MOV DOWN ACC
JNZ C
SWP
MOV 2 DOWN
MOV ACC DOWN

@3
L:MOV UP ACC
MOV ACC UP
MOV ACC UP
MOV ACC DOWN
MOV UP DOWN
JNZ L
MOV UP ACC
G:MOV ACC DOWN
ADD 1
JRO DOWN
JMP L
JMP G

@5
L:SUB UP
SWP
ADD 1
SWP
JRO UP
G:SWP
ADD UP
SWP
MOV ACC UP
SUB 1
JNZ G
SWP
MOV ACC DOWN
MOV 0 ACC
