Vida Na Praia is right. The IATA code for Sao Paulo is SAO. Despite of almost all int'l flights from/to Sao Paulo uses GRU airport, it is located at Guarulhos city.
Using GRU to refer to Sao Paulo city is almost the same as using EWK to refer to New York city ^
I thought CGH is the main one. That is where I flew in from SDU. (Added, I mean main city airport in São Paulo)