Caleb, Andy and Billy went on a picnic with their father. Billy took 6 candies with him, Caleb took 11 and Andy left with 9. On the way, their father bought a packet of 36 candies. He gave 8 candies to Billy, 11 to Caleb and the rest to Andy. How many more candies does Andy now have than Caleb?
Please reason step by step, and put your final answer within \boxed{}.
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