i cant see any connection between hint and the question
You have not got all of the hint. It is warning you that $\displaystyle 13^{10^6}$ will be out of range for the integer type in the programming language you choose, for the range of witness and candidate primes that your algorithm is required to operate over (and I suspect it is also suggesting that you decompose your exponents into binary and compute the powers incrementally modulo $\displaystyle p$)
CB