def _get_sss_rank(sss):
    """Get SSS rank."""
    inside = sss['sss_info']['in_order']
    nfree = (inside + 1) ** 2 - 1
    nfree -= (len(sss['sss_info']['components'][:nfree]) -
              sss['sss_info']['components'][:nfree].sum())
    return nfree