May first is celebrated by fans of Melody due to the degree to which the Bee Gees song First of May inspired the story told in the film, and due to its inclusion in the film as the theme of Daniel and Melody. It is played starting when they officially “get together” when she makes unambiguously clear she returns his interest. In the movie, it plays as they go from the school to the overgrown cemetery, then is reprised after the famous cemetery scene and as they walk to her apartment to have tea with her family. That’s on YouTube as First of May, Cemetery Scene, Melody (1971).
This embed is my favorite version that creates a music video for First of May from scenes clipped from the movie, covering a lot of that part of the story, without sticking exclusively to the part around the cemetery scene.
This is a much happier observation of May first than the increasingly widely observed Victims of Communism Day. But we should certainly remember them as well.