The Marker lies among the first three markers. The slip shifts to the next marker each time you uncover it. So if you get it at position 2, then for the next rival it would be at position 3, and if it is on position 3 then it would be at position 1 the next time. so it is crucial to find it once at the first rival.
If that also doesn’t have the pink slip then obviously the remaining one of the three has got the pink slip.
