Imagine that you work for an insurance company that is insuring people against identity theft. You have just learned about a major security breach at a prominent bank used by many of your customers. Through back channels, you have obtained the list of Social Security numbers of the bank customers whose banking records were stolen, and, of course, you know the Social Security numbers for your own customers. Describe an efficient scheme for identifying which of your customers were victims in this security breach. What is the running time of your method in terms of n, the number of customers of your insurance company, and m, the number of bank customers who were victims in this security breach?