Is it permissible to feed one needy person for thirty days, or to feed thirty needy people on one day for one who is unable to fast?

One who is continuously unable to fast must feed a poor person for each day he misses, based on the Almighty’s saying: "And upon those who are able to fast, but with difficulty, is a ransom: the feeding of a poor person." There are two ways to feed: either by preparing food and inviting the poor to it, or by giving them uncooked food. It is permissible to feed one poor person for thirty days, or to gather thirty poor persons for one meal.