At an ever increasing pace Al, Bert and Charlie have been receiving into three identical boxes of limitless capacity identical pairs of silver coins engraved with the integers 1, 2, 3, 4, ... etc. These events occur on a precise schedule, each box receiving
Coins marked 1 and 2 at 1 minute before midnight
Coins marked 3 and 4 at 1/2 minute before midnight
Coins marked 5 and 6 at 1/4 minute before midnight
Coins marked 7 and 8 at 1/8 minute before midnight
etc.
But they were instructed at each event to remove a coin from their respective boxes and discard it. After some thought, Al decided each time to discard his lowest-numbered coin; Bert discarded an even-numbered coin; and Charlie thought what the heck and discarded a coin selected at random. Regardless of strategy, at each event the number of coins in each box grew by unity, so that after N events each box held N coins.
Needless to say when midnight struck their arms were infinitely tired, but it was a small price to pay for infinite riches. But tell us, now, whether their expectations were met.
Describe the contents of each box at midnight.