# Codeblock 5b
    target_bbox = target[..., 21:25]      #(1)
    
    pred_bbox0 = prediction[..., 21:25]   #(2)
    pred_bbox1 = prediction[..., 26:30]   #(3)
    
    iou_pred_bbox0 = intersection_over_union(pred_bbox0, target_bbox)  #(4)
    iou_pred_bbox1 = intersection_over_union(pred_bbox1, target_bbox)  #(5)
    
    iou_pred_bboxes = torch.cat([iou_pred_bbox0.unsqueeze(0), 
                                 iou_pred_bbox1.unsqueeze(0)], 
                                dim=0)
    
    best_iou, best_bbox_idx = torch.max(iou_pred_bboxes, dim=0)    #(6)
    
    target_bbox = obj * target_bbox                                #(7)
    best_bbox   = obj * (best_bbox_idx*pred_bbox1                  #(8)
                         + (1-best_bbox_idx)*pred_bbox0)

    target_bbox[..., 2:4] = torch.sqrt(target_bbox[..., 2:4])      #(9)
    best_bbox[..., 2:4]   = torch.sign(best_bbox[..., 2:4]) * torch.sqrt(torch.abs(best_bbox[..., 2:4]) + 1e-6)  #(10)

    bbox_loss = sse(          #(11)
        torch.flatten(target_bbox, end_dim=-2),
        torch.flatten(best_bbox, end_dim=-2)
    )