for (y = 1; y <= Bottom; y++) {
  if (pos([3,y], "◎") > 0) {
    [2,y] = "◎";
  } else if (pos([3,y], "□") > 0) {
    [2,y] = "□";
  } else if (pos([3,y], "◆") > 0) {
    [2,y] = "◆";
  }
}