answer : language is regular
Explanation :
if you observe the language, once u get 'ab' then on the next string u could get am 'a' or 'b' making 'ba' or waiting for 'a' because on the input 'b' again. So at any point of time u can have the difference of 'ab' and 'ba' to be at most 1, not more than that. thus reducing the power of the language of a regular language.
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