Definition: In this task, you're given a four sentences of story written in natural language. Your job is to complete end part of the story by predicting appropriate last sentence which is coherent with the given sentences.
Input: Sentence1: Carl joined the military right after high school. Sentence2: He signed a short contract that put him on the front lines. Sentence3: His best friend was killed in front of him. Sentence4: Happiness became a foreign concept to Carl.

Carl had to go to therapy for post-traumatic stress disorder.