DEFINE MAX_SIZE="10"
DEFINE MAX_MATRIX_SIZE="100"

INT FUNC Index(BYTE size,x,y)
RETURN (x+y*size)

PROC PrintMatrix(BYTE ARRAY a BYTE size)
  BYTE i,j,v

  FOR j=0 TO size-1
  DO
    FOR i=0 TO size-1
    DO
      v=a(Index(size,i,j))
      IF v<10 THEN
        Print("  ")
      ELSE
        Print(" ")
      FI
      PrintB(v)
    OD
    PutE()
  OD
RETURN

PROC FillMatrix(BYTE ARRAY a BYTE size)
  BYTE start,end
  INT dir,i,j

  start=0 end=size*size-1
  i=0 j=0 dir=1

  DO
    a(Index(size,i,j))=start
    a(Index(size,size-1-i,size-1-j))=end
    start==+1 end==-1
    i==+dir j==-dir
    IF i<0 THEN
      i==+1 dir=-dir
    ELSEIF j<0 THEN
      j==+1 dir=-dir
    FI
  UNTIL start>=end
  OD

  IF start=end THEN
    a(Index(size,i,j))=start
  FI
RETURN

PROC Test(BYTE size)
  BYTE ARRAY mat(MAX_MATRIX_SIZE)

  PrintF("Matrix size: %B%E",size)
  FillMatrix(mat,size)
  PrintMatrix(mat,size)
  PutE()
RETURN

PROC Main()
  Test(5)
  Test(6)
RETURN