Brazilian President Dilma Rousseff visited the state of Sao Paulo after the region was hit by flood that killed over 20 people.Observing the situation from a helicopter, on Saturday she said that the government had allocated funds to help the affected areas, Xinhua reported."The priority when faced with natural disasters is prevention. This means working to avoid more deaths, to rebuild damaged infrastructure, to clean towns and to repair streets, so that life can get back to normal," she said.Strong rains, causing flooding and landslides on Friday, have left at least 20 dead and five missing in the towns of Maripora, Francisco Morato, Itapevi, Itatiba, Guarulhos and Cajamar.The flooding has also cut off highways, suspended rail services and led to the closing of the airports in Congonhas and Guarulhos for several hours.