15. Two individuals, A and B, start from points $A$ and $B$ respectively at the same time, and continuously travel back and forth between $A$ and $B$. When A reaches $B$ for the 5th time, B happens to return to $B$ for the 9th time. Then, when A reaches $B$ for the 2015th time, the two individuals have met $\qquad$ times (both head-on encounters and overtakes are counted as meetings, and if they arrive at $B$ simultaneously, it counts as one meeting).
【Analysis】When A reaches B for the 5th time, A has walked 9 full journeys, at this point B has walked 18 full journeys; so B's speed is twice that of A. If B takes 1 unit of time to walk a full journey, then A takes 2 units of time to walk a full journey. Draw a Liuka diagram:
When A reaches B for the 2015th time, A has walked $1+2014 \times 2=4029$ full journeys, taking $4029 \times 2=8058$ units of time, $8058 \div 4=2014 \ldots 2$ $2014 \times 3+2=6044$ (times)