Ten hats were hung on pegs as shown in the illustration—five
silk hats and five felt "bowlers," alternately silk and felt.
The two pegs at the end of the row were empty. Remove two
contiguous hats to the vacant pegs, then two other adjoining
hats to the pegs now unoccupied, and so on until five pairs have
been moved and the hats again hang in an unbroken row, but with
all the silk ones together and all the felt Remember, the two
hats removed must always be contiguous ones, and you must take
one in each hand and place them on their new pegs without
reversing their relative position. You are not allowed to cross
your hands, nor to hang up one at a time. Try it with counters
of two colours or with coins, and remember that the two empty
pegs must be left at one end of