def stations_highest_rel_level(stations, N):
    """Given a list of stations, returns N stations at highest risk of flooding"""
    def rel_level(x):
        level = x.relative_water_level()
        if level == None:
            return -69669696969669696969699420
        return level
   
    stations.sort(key=rel_level, reverse=True)
    return stations[:N]