The Long Walk (1970)

In a dystopian near-future, 100 teenage boys must embark on an annual competitive test known as "The Long Walk". The rules are simple: maintain a speed above 4 miles per hour. Receive three warnings in an hour and you’re shot dead. The last one walking gets whatever he wants for the rest of his life. Under these grim circumstances the boys develop deep friendships despite knowing that each of their friends’ survival is a threat to their own.