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:
| Driver | Constructor | Laps | Time/Retired | Grid |
| --- | --- | --- | --- | --- |
| Niki Lauda | McLaren - TAG | 70.0 | 1:32:29.263 | 10.0 |
| Alain Prost | McLaren - TAG | 70.0 | + 0.232 | 3.0 |
| Ayrton Senna | Lotus - Renault | 70.0 | + 48.491 | 4.0 |
| Michele Alboreto | Ferrari | 70.0 | + 48.837 | 16.0 |
| Elio de Angelis | Lotus - Renault | 69.0 | + 1 Lap | 11.0 |
| Nigel Mansell | Williams - Honda | 69.0 | + 1 Lap | 7.0 |
| Martin Brundle | Tyrrell - Renault | 69.0 | + 1 Lap | 21.0 |
| Nelson Piquet | Brabham - BMW | 69.0 | + 1 Lap | 1.0 |
| Gerhard Berger | Arrows - BMW | 68.0 | + 2 Laps | 14.0 |
| Marc Surer | Brabham - BMW | 65.0 | Exhaust | 9.0 |
| Huub Rothengatter | Osella - Alfa Romeo | 56.0 | Not Classified | 26.0 |
| Thierry Boutsen | Arrows - BMW | 54.0 | Suspension | 8.0 |
| Philippe Alliot | RAM - Hart | 52.0 | Engine | 25.0 |
| Stefan Bellof | Tyrrell - Renault | 39.0 | Engine | 22.0 |
| Derek Warwick | Renault | 27.0 | Gearbox | 12.0 |
| Andrea de Cesaris | Ligier - Renault | 25.0 | Turbo | 18.0 |
| Patrick Tambay | Renault | 22.0 | Transmission | 6.0 |
| Keke Rosberg | Williams - Honda | 20.0 | Engine | 2.0 |
| Teo Fabi | Toleman - Hart | 18.0 | Wheel Bearing | 5.0 |
| Jacques Laffite | Ligier - Renault | 17.0 | Electrical | 13.0 |
| Jonathan Palmer | Zakspeed | 13.0 | Oil Pressure | 23.0 |
| Piercarlo Ghinzani | Toleman - Hart | 12.0 | Engine | 15.0 |
| Stefan Johansson | Ferrari | 9.0 | Engine | 17.0 |
| Pierluigi Martini | Minardi - Motori Moderni | 1.0 | Accident | 24.0 |
| Eddie Cheever | Alfa Romeo | 1.0 | Turbo | 20.0 |
| Riccardo Patrese | Alfa Romeo | 1.0 | Turbo | 19.0 |
Question:
What is the smallest grid for Ayrton Senna?
Answer:
4.0