[START]
-opt-
:per
30
-optend-
:addcarry
8
   
500
50
60
20
[END]
[START]
-opt-
:per
30
-optend-
:addcarry
8
   
600
60
70
20
[END]
[START]
-opt-
:obvious
-optend-
:addcarry
8
  ü 
900
90
80
23
[END]