Article: The two became friends, and for many years lived in close proximity in Paris, Chopin at 38 Rue de la Chaussée-d'Antin, and Liszt at the Hôtel de France on the Rue Lafitte, a few blocks away. They performed together on seven occasions between 1833 and 1841. The first, on 2 April 1833, was at a benefit concert organized by Hector Berlioz for his bankrupt Shakespearean actress wife Harriet Smithson, during which they played George Onslow's Sonata in F minor for piano duet. Later joint appearances included a benefit concert for the Benevolent Association of Polish Ladies in Paris. Their last appearance together in public was for a charity concert conducted for the Beethoven Memorial in Bonn, held at the Salle Pleyel and the Paris Conservatory on 25 and 26 April 1841.

Question: How many times did Frédéric and Liszt collaborate in performances during the years of 1833 to 1841?
seven