'move up=1 right=2 down=3 left=4
' ---------------------------------
dim plane(100,100)
x  = 50: y = 50
mx = 100

while (x>0) and (x<100) and (y>0) and (y<100)
if plane(x,y) then
   nxt = nxt - 1
   if nxt < 1 then nxt = 4
  else
   nxt = nxt + 1
   if nxt > 4 then nxt = 1
end if

x          = x + (nxt = 2) - (nxt = 4)
y          = y + (nxt = 3) - (nxt = 1)
plane(x,y) = (plane(x,y) <> 1)
mx         = min(x,mx)
wend

for x = mx to 100
  for y = 1 to 100
   print chr$((plane(x,y)*3) + 32);
  next y
  print x
next x