Read this and answer the question. If the question is unanswerable, say "unanswerable".

Spielberg has filmed and is currently in post-production on an adaptation of Roald Dahl's celebrated children's story The BFG. Spielberg's DreamWorks bought the rights in 2010, originally intending John Madden to direct. The film was written by E.T. screenwriter Melissa Mathison and is co-produced by Walt Disney Pictures, marking the first Disney-branded film to be directed by Spielberg. The BFG is set to premiere out of competition at the Cannes Film Festival in May 2016, before its wide release in the US on July 1, 2016.

What was the first movie written by Melissa Mathison?
unanswerable