Very interesting premise. Simple system. My only issue was that sometimes it didn't seem to have a rhyme or reason to which file it grabbed when multiple were stacked on top of each other. Sometimes it would grab the top one, sometimes the bottom, sometimes one in between those two.
Other than that my only suggestions to improvement would be to add a timer so that you know how much longer you have to go for that section.
Great work - even in this simplistic form it would make a fantastic minigame for any modern setting. And with a more fleshed out level progression format you could make a little game out of it For instance you rise through the ranks of an office building with the first level being just 1 green and 1 pink. Then you move on to 2 of each type, then you get your first order of shredding unwanted things, then it progresses to there.
Nonetheless, great effort and a fun premise.