MODULE auto;
CONST n = 79;           (* number of elements *)
      m = (n+1) DIV 2;  (* number of loops *)
CONFIGURATION list [1..n];
CONNECTION left:  list[i] -> list[i-1];
           right: list[i] -> list[i+1];

VAR i  : INTEGER;
    val: list OF BOOLEAN;
    c  : list OF ARRAY BOOLEAN OF CHAR;

BEGIN
  val      :=  ID(list) = m; (* Init *)
  c[FALSE] :=  " ";
  c[TRUE]  :=  "X";
  FOR i:= 1 TO m DO
    Write(c[val]);
    val := MOVE.left(val) <> MOVE.right(val);
  END;
END auto.