Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Pos | No | Driver | Constructor | Laps | Time/Retired | Grid | Points |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 15 | Sebastian Vettel | Red Bull-Renault | 56 | 1:57:43.485 | 1 | 10 |
| 2 | 14 | Mark Webber | Red Bull-Renault | 56 | +10.970 | 3 | 8 |
| 3 | 22 | Jenson Button | Brawn-Mercedes | 56 | +44.975 | 5 | 6 |
| 4 | 23 | Rubens Barrichello | Brawn-Mercedes | 56 | +1:03.704 | 4 | 5 |
| 5 | 2‡ | Heikki Kovalainen | McLaren-Mercedes | 56 | +1:05.102 | 12 | 4 |
| 6 | 1‡ | Lewis Hamilton | McLaren-Mercedes | 56 | +1:11.866 | 9 | 3 |
| 7 | 10 | Timo Glock | Toyota | 56 | +1:14.476 | 19 | 2 |
| 8 | 12 | Sébastien Buemi | Toro Rosso-Ferrari | 56 | +1:16.439 | 10 | 1 |
| 9 | 7 | Fernando Alonso | Renault | 56 | +1:24.309 | 2 |  |
| 10 | 4 | Kimi Räikkönen | Ferrari | 56 | +1:31.750 | 8 |  |
| 11 | 11 | Sébastien Bourdais | Toro Rosso-Ferrari | 56 | +1:34.156 | 15 |  |
| 12 | 6‡ | Nick Heidfeld | BMW Sauber | 56 | +1:35.834 | 11 |  |
| 13 | 5 | Robert Kubica | BMW Sauber | 56 | +1:46.853 | 17 |  |
| 14 | 21 | Giancarlo Fisichella | Force India-Mercedes | 55 | +1 Lap | 20 |  |
| 15 | 16 | Nico Rosberg | Williams-Toyota | 55 | +1 Lap | 7 |  |
| 16 | 8 | Nelson Piquet, Jr. | Renault | 54 | +2 Laps | 16 |  |
| 17 | 20 | Adrian Sutil | Force India-Mercedes | 50 | Accident | 18 |  |
| Ret | 17 | Kazuki Nakajima | Williams-Toyota | 43 | Transmission | 14 |  |
| Ret | 3 | Felipe Massa | Ferrari | 20 | Electrical | 13 |  |
| Ret | 9 | Jarno Trulli | Toyota | 18 | Collision damage | 6 |  |
Question:
how many drivers did not finish 56 laps?
Answer:
7