|Rd.|Grand Prix|Date|Location|Pole Position|Fastest Lap|Winning Driver|Constructor|Report|
|---|---|---|---|---|---|---|---|---|
|1|Brazilian Grand Prix|26 March|Jacarepaguá|Ayrton Senna|Riccardo Patrese|Nigel Mansell|Ferrari|Report|
|2|San Marino Grand Prix|23 April|Imola|Ayrton Senna|Alain Prost|Ayrton Senna|McLaren-Honda|Report|
|3|Monaco Grand Prix|7 May|Monaco|Ayrton Senna|Alain Prost|Ayrton Senna|McLaren-Honda|Report|
|4|Mexican Grand Prix|28 May|Hermanos Rodríguez|Ayrton Senna|Nigel Mansell|Ayrton Senna|McLaren-Honda|Report|
|5|United States Grand Prix|4 June|Phoenix|Ayrton Senna|Ayrton Senna|Alain Prost|McLaren-Honda|Report|
|6|Canadian Grand Prix|18 June|Circuit Gilles Villeneuve|Alain Prost|Jonathan Palmer|Thierry Boutsen|Williams-Renault|Report|
|7|French Grand Prix|9 July|Paul Ricard|Alain Prost|Maurício Gugelmin|Alain Prost|McLaren-Honda|Report|
|8|British Grand Prix|16 July|Silverstone|Ayrton Senna|Nigel Mansell|Alain Prost|McLaren-Honda|Report|
|9|German Grand Prix|30 July|Hockenheimring|Ayrton Senna|Ayrton Senna|Ayrton Senna|McLaren-Honda|Report|
|10|Hungarian Grand Prix|13 August|Hungaroring|Riccardo Patrese|Nigel Mansell|Nigel Mansell|Ferrari|Report|
|11|Belgian Grand Prix|27 August|Spa-Francorchamps|Ayrton Senna|Alain Prost|Ayrton Senna|McLaren-Honda|Report|
|12|Italian Grand Prix|10 September|Monza|Ayrton Senna|Alain Prost|Alain Prost|McLaren-Honda|Report|
|13|Portuguese Grand Prix|24 September|Estoril|Ayrton Senna|Gerhard Berger|Gerhard Berger|Ferrari|Report|
|14|Spanish Grand Prix|1 October|Jerez|Ayrton Senna|Ayrton Senna|Ayrton Senna|McLaren-Honda|Report|
|15|Japanese Grand Prix|22 October|Suzuka|Ayrton Senna|Alain Prost|Alessandro Nannini|Benetton-Ford|Report|
|16|Australian Grand Prix|5 November|Adelaide|Ayrton Senna|Satoru Nakajima|Thierry Boutsen|Williams-Renault|Report|

Question: how many races occurred before alain prost won a pole position?
Answer: 5