Ghosh Babu surveyed his companies and obtained the following data. Income tax is paid from profit before tax and the remaining amount is apportioned to dividend and retained earnings. The retained earnings were accumulated into reserves. The reserves at the beginning of $1991$ were Rs. $80$ lakh.
| Figure (Rs. in lakh) | $1994$ | $1993$ | $1992$ | $1991$ |
|---|---|---|---|---|
| Share capital | $0310$ | $0205$ | $0098$ | $0098$ |
| Sales | $6435$ | $4725$ | $2620$ | $3270$ |
| Profit before tax | $0790$ | $0525$ | $0170$ | $0315$ |
| Dividends | $0110$ | $0060$ | $0030$ | $0030$ |
| Retained earnings | $0400$ | $0245$ | $0070$ | $0140$ |




| A | B | C | D | Average |
|---|---|---|---|---|
| 3 | 4 | 4 | ? | 4 |
| 3 | ? | 5 | ? | 4 |
| ? | 3 | 3 | ? | 4 |
| ? | ? | ? | ? | 4.25 |
| 4 | 4 | 4 | 4.25 |
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: