Question about the solution to Unexpected hanging paradox The following is the unexpected hanging paradox:
A judge tells a condemned prisoner that he will be hanged at noon on one weekday in the following week but that the execution will be a surprise to the prisoner. He will not know the day of the hanging until the executioner knocks on his cell door at noon that day.
Having reflected on his sentence, the prisoner draws the conclusion that he will escape from the hanging. His reasoning is in several parts. He begins by concluding that the "surprise hanging" can't be on Friday, as if he hasn't been hanged by Thursday, there is only one day left - and so it won't be a surprise if he's hanged on Friday. Since the judge's sentence stipulated that the hanging would be a surprise to him, he concludes it cannot occur on Friday.
He then reasons that the surprise hanging cannot be on Thursday either, because Friday has already been eliminated and if he hasn't been hanged by Wednesday night, the hanging must occur on Thursday, making a Thursday hanging not a surprise either. By similar reasoning he concludes that the hanging can also not occur on Wednesday, Tuesday or Monday. Joyfully he retires to his cell confident that the hanging will not occur at all.
The next week, the executioner knocks on the prisoner's door at noon on Wednesday — which, despite all the above, was an utter surprise to him. Everything the judge said came true.
The solution given is the following:
Formulation of the judge's announcement into formal logic is made difficult by the vague meaning of the word "surprise". An attempt at formulation might be:
The prisoner will be hanged next week and the date (of the hanging) will not be deducible the night before from the assumption that the hanging will occur during the week (A).
Given this announcement the prisoner can deduce that the hanging will not occur on the last day of the week. However, in order to reproduce the next stage of the argument, which eliminates the penultimate day of the week, the prisoner must argue that his ability to deduce, from statement (A), that the hanging will not occur on the last day, implies that a last-day hanging would not be surprising. But since the meaning of "surprising" has been restricted to not deducible from the assumption that the hanging will occur during the week instead of not deducible from statement (A), the argument is blocked.
my question Why should the prisoner argue that his ability to deduce, from statement (A), that the hanging will not occur on the last day, implies that a last-day hanging would not be surprising? I can't understand the solution.
Can anyone kindly explain to me please? 
 A: The day of the hanging can be either Monday, Tuesday or Wednesday for it to be a surprise. I define Monday, Tuesday, Wednesday and Thursday as "flexible options" while Friday is a "non flexible option" as its conclusion is apparent without any further data. The solution is to have more than one flexible option to have doubt.
It can't be Friday as past noon on Thursday if he is not hanged he knows the day for the hanging to be Friday thus he can't be surprised on Friday.
It can't be Thursday as past noon Wednesday if he is not hanged he can't be surprised on Thursday knowing that being surprised on Friday is not an option, whatever be the outcome on Thursday. Friday isn't an option in any scenario from the beginning as it leaves the inevitable result obvious after noon Thursday. Therefore after noon Wednesday if he is not hanged he cannot be surprised as Thursday is the only flexible option left.
But before noon on Wednesday he has two flexible options Wednesday and Thursday on which he can't be sure on. Noon on Wednesday is the last possible time to surprise the prisoner after that he can't be surprised as described above. 
