  Given an integer base $b>1$, a set of integers is represented in base $b$ by
a language over $\{0,1,...,b-1\}$. The set is said to be $b$-recognisable if
its representation is a regular language. It is known that eventually periodic
sets are $b$-recognisable in every base $b$, and Cobham's theorem implies the
converse: no other set is $b$-recognisable in every base $b$.
  We are interested in deciding whether a $b$-recognisable set of integers
(given as a finite automaton) is eventually periodic. Honkala showed that this
problem decidable in 1986 and recent developments give efficient decision
algorithms. However, they only work when the integers are written with the
least significant digit first.
  In this work, we consider the natural order of digits (Most Significant Digit
First) and give a quasi-linear algorithm to solve the problem in this case.
