Task: Question Answering
Input (English): Passage: Every year, 12-year old Samuel, 10-year old Jeffrey and 8-year old Michael Douglas visit their grandfather, Mori Tanaka at his cabin. Mori trains his grandchildren in the art of Ninjutsu. As the summer comes to an end, Mori gives each of them a new "ninja" name based on their personalities: 'Rocky', 'Colt', and 'Tum-Tum'. 
Meanwhile, the boys' father, Sam Douglas, is an FBI agent who stages a sting operation to entrap Hugo Snyder in the sale of warheads. Snyder escapes the trap with the use of his own ninja henchmen. Snyder decides to test Mori's fighting skill. The boys ignore Mori's orders to stay in the house and aid by defeating two ninjas on their own. Snyder threatens Mori's family if he doesn't get Douglas off his back, and Mori chides the boys briefly for interfering in his personal affairs. When they return home, they find their father unenthusiastic to see what they had learned during their visit and more annoyed at their new names. Emily, a friend of Rocky's, compliments his new name and agrees to ride with them to school the next day. Snyder develops a plan to kidnap the boys to use them as leverage to get Douglas to back off. Since the FBI watches them, his assistant Brown contacts his nephew Fester and his buddies Hammer and Marcus to kidnap the boys. Due to Douglas and his FBI crew's presence, they are unable to capture the boys. 
Question: What is the last name of the man that is annoyed by the new names of his kids?
Output (English): Douglas.