burnt

How should a person who drowned or burnt to death be given ghusal?

Q:

1. If a person’s body was completely burnt, how should one carry out the ghusal?

2. Similarly, how should ghusal be carried out in cases where it is difficult to perform the ghusal (e.g. advanced stages of decomposition or a person drowned and his body was recovered after many days, due to which the flesh and skin are coming apart and disintegrating)?