def get_max_id(key_dict):
    """
    Gets the max id found inside a key_dict keys
    
    :param key_dict: Dict containing the correspondance between contigs and contig maps
    :type key_dict: dict((int, int, int), (str, int, int, int))
    :return: Maximum value of the key_dict keys
    :rtype: int
    """
    max_id = 0
    for map_id, _, _ in key_dict:
        if max_id < map_id:
            max_id = map_id
    return max_id
