Exchange problem

Its new year time and your company has sent T-Shirts of varying sizes from HQ (read US). The problem is that the sizes in US and the sizes in India don't really match. So a guy with L size in India would like to settle for M size in US, one with XXL in India would like to go for XL and so on. Employees in India are bugged up and want to exchange it with appropriate sized T-Shirt. Now that the management didn't take care of it before sending the T-Shirts to India, you have been assigned by the Indian management to arrange an exchange between the employees. How would you go about it? Also describe your algorithm. If all this information is stored in the database, write a query that would do the job.