Check sequence in which sprites are overlapped

[kray]

I have a game in which sprites(letters) will be falling from the top and the player has to collect the sprites in a specific order. 
The trouble I'm having is, how do I keep track of the order in which the player is collecting the sprites?

[Akshar Patel]

Add a custom property to identify the sprites and have an array that will store the identities of overlaps. As and when the overlap happens, push the identifying property to the array. Now you can check the sequence of the overlaps.