$ include "seed7_05.s7i";

const type: direction is new enum UP, RIGHT, DOWN, LEFT end enum;

const proc: main is func
  local
    const integer: width is 75;
    const integer: height is 52;
    var array array boolean: m is height times width times FALSE;
    var direction: dir is UP;
    var integer: x is width div 2;
    var integer: y is height div 2;
  begin
    while x in {1 .. width} and y in {1 .. height} do
      dir := direction conv ((ord(dir) + 2 * ord(m[y][x]) - 1) mod 4);
      m[y][x] := not m[y][x];
      case dir of
        when {UP}:    decr(y);
        when {RIGHT}: decr(x);
        when {DOWN}:  incr(y);
        when {LEFT}:  incr(x);
      end case;
    end while;
    for key x range m do
      for y range 1 to width do
        write(".#"[succ(ord(m[x][y]))]);
      end for;
      writeln;
    end for;
  end func;