def merge_dicts(dict1, dict2):
    for key, value in dict2.items():
        if key in dict1:
            if isinstance(value, dict):
                merge_dicts(dict1[key], value)
            elif isinstance(value, list):
                dict1[key].extend(value)
            else:
                dict1[key] = value
        else:
            dict1[key] = value