Sometimes movies got remade. And then remakes are remade again and so on. For example, the movie Lost Patrol by Walter Summers was released in 1929. It was remade in 1934 by John Ford. This remake was used as a basis for the Soviet movie The Thirteen (1937) by Mikhail Romm. In 1943 Romm's movie was adapted in Sahara by Zoltán Korda. And the former movie was remade twice: in 1953 and 1995.
So the length of the chain is 4. What's the longest chain of remakes? Note, that if a movie has 4 remakes, it's still the length of 1, I'm interested in remakes of remakes.