Please answer the following question: Extract the answer to the following question from the movie plot. If the question isn't answerable, please output "Can't answer". Question: Whose body do Oskar's fellow students find during an ice skating field trip at the lake? Title: Let the Right One In Movie plot: Twelve year old Oskar (Kare Hedebrant) is so wimpy that he's constantly picked on by the other boys at his school, especially Conny (Patrik Rydmark) and his two friends, Martin (Mikael Erhardsson) and Andreas (Johan Somnes). Out of fear, Oskar never fights back. In the evenings, however, he sits in the courtyard rehearsing knife attacks on his tormentors. One evening, Oskar notices a new girl about his age and her father moving into into #15, the apartment next door to his. Oddly, the first thing they do is to cover the windows with cardboard. What Oskar doesn't know is that Hakan(Per Ragnar) is not Eli (Lina Leandersson)'s father... he is her renfield... and Eli is a vampire. It is Hakan's job to bring Eli fresh blood, which he gets by killing other humans. First he anesthetizes them with halothane, then he strings them up by the feet, slits their necks, and catches the blood in a jug, leaving the bodies to be discovered the next day. Unfortunately for Eli, Hakan is having problems securing blood for her. On his first kill after moving into the new apartment, he either lost or forgot the jug filled with blood. Consequently, Eli is beginning to get hungry.One evening, as Oskar is in the courtyard stabbing a tree in lieu of his tormentors, he notices Eli watching him. She's not very friendly, as she tells him right off that she can't be friends with him. The next evening, they run into each other again in the courtyard. Oskar notices that Eli is not wearing a coat even though it's the dead of winter in Stockholm. What's more, she's not even cold. And she smells bad. Still, Oskar shares with her his Rubik's cube and shows her how to work it. After Oskar has gone inside, Eli goes hunting. She waits in the shadows under a bridge. When two neighborhood friends, Jocke (Mikael Rahm) and Lacke (Peter Carlberg), part company, and Jocko walks under the bridge, Eli calls out, "Help me!" Thinking that the little girl has fallen, Jocko picks her up. Suddenly, Eli latches onto him and bites his neck. Gosta (Karl-Robert...
A:
They find only Jocko's blood. The body has disappeared.