73. There are $N$ chess pieces placed on a circle, as shown in the figure, with a chess piece at point $B$ adjacent to the chess piece at point $A$. Xiaohong first takes away 1 chess piece from point $B$, then moves clockwise, taking away 2 chess pieces every 1 piece, and continues for 10 rounds, crossing $A$ 9 times. When about to cross $A$ for the 10th time to take a chess piece, Xiaohong finds that there are more than 20 chess pieces left on the circle. If $N$ is a multiple of 14, then there are $\qquad$ chess pieces left on the circle.
answer: 23