I would suggest that the introduction to the Letter from Birmingham Jail contains five paragraphs, concluding with "it is even more unfortunate that the city's white power structure left the Negro community with no alternative." These paragraphs provide the background, the historic developments that led to his actions in Birmingham.
I count 41 paragraphs in the body of the letter; the detailed recounting of the basis for the actions taken, the encounters with other groups, the reaction and lack of action experienced at numerous points, the determination of new tactics brought about by the perceived need to create change in new ways since old practices were proving ineffective, the justification of measures taken and attempts to reconcile those measures with opposing viewpoints, the expression of frustration, disappointment, and hope.
The concluding three paragraphs apologize for the length of the letter and express hope for future opportunities.
This question has been previously asked (by you) and answered right here on eNotes. Here is the link for you: http://www.enotes.com/martin-luther-king-jr/q-and-a/letter-from-birmingham-jail-by-mlk-how-many-265055