BYTE FUNC Damm(CHAR ARRAY a)
  BYTE ARRAY table=[
    0 3 1 7 5 9 8 6 4 2
    7 0 9 2 1 5 4 8 6 3
    4 2 0 6 8 7 1 3 5 9
    1 7 5 0 9 8 3 4 2 6
    6 1 2 3 0 4 5 9 7 8
    3 6 7 4 2 0 9 5 8 1
    5 8 6 9 7 2 0 1 3 4
    8 9 4 5 3 6 2 0 1 7
    9 4 3 8 6 1 7 2 0 5
    2 5 8 1 4 3 6 7 9 0]
  BYTE i,x,c

  x=0
  FOR i=1 TO a(0)
  DO
    c=a(i)
    IF c<'0 OR c>'9 THEN
      RETURN (0)
    FI
    c==-'0
    x=table(x*10+c)
  OD
  IF x=0 THEN
    RETURN (1)
  FI
RETURN (0)

PROC Test(CHAR ARRAY a)
  BYTE i

  Print(a) Print(" -> ")
  IF Damm(a)=1 THEN
    PrintE("valid")
  ELSE
    PrintE("invalid")
  FI
RETURN

PROC Main()
  Test("5724")
  Test("5727")
  Test("112946")
  Test("112949")
RETURN