2015 flags are planted equidistantly on the circular runway. A and B start from a certain flag at the same time. When A and B return to the starting point at the same time again, A runs 23 laps and B runs 13 laps. Not counting the flag position at the starting point, how many times does A catch up to B exactly at the flag position?
圆形跑道上等距插着2015面旗子，甲与乙同时同向从某个旗子出发，当甲与乙再次同时回到出发点时，甲跑了23圈，乙跑了13圈．不算起始点旗子位置，则甲正好在旗子位置追上乙多少次？
<result>4</result>