How are successive exceptions interpreted when the initial statement is affirmative and subsequent exceptions alternate between negation and affirmation?

Primary text

When the commencement of the speech is affirmative, the first exception acts as a negation, and the second exception acts as an affirmation. If a third exception follows, it reverts to negation, with each exception relating back to the immediately preceding clause. Thus, if someone states, 'I owe him ten, except for three, except for one dirham,' the speaker affirms eight. This is because ten was affirmed, then three was negated (leaving seven), and then one dirham was affirmed (seven plus one equals eight). The remaining two dirhams from the initially negated three are treated as excepted from the original ten, leaving eight owed.