- Roy is heavier than Abhishek.
- Both Roy and Abhishek are taller and heavier than Das.
Therefore, Das is shorter and lighter than both Roy and Abhishek.
- Vivek is lighter than Abhishek.
- Ranjan is heavier than Das but shorter than Das.
- Given that Roy is heavier than Das, the statements imply Abhishek is taller than Roy.
- Vivek is heavier than Ranjan.
- Das is lighter than Roy and Abhishek.
- Ranjan is heavier than Das.
- Vivek is lighter than Abhishek but still heavier than Das (since Das is the lightest overall).
\[ \boxed{\text{Das}} \]





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: