Answer the questions based on the following information.
In a locality, there are five small cities: A, B, C, D and E. The distances of these cities from each other are as follows.
$AB = 2 \ \mathrm{km}$ $AC = 2 \ \mathrm{km}$ $AD > 2 \ \mathrm{km}$ $AE > 3 \ \mathrm{km}$ $BC = 2 \ \mathrm{km}$
$BD = 4 \ \mathrm{km}$ $BE = 3 \ \mathrm{km}$ $CD = 2 \ \mathrm{km}$ $CE = 3 \ \mathrm{km}$ $DE > 3 \ \mathrm{km}$





For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: