I am trying to use pins 51 through 53 (on an Arduino Mega 2560) as digital inputs, however the program does not work when doing so. It works when I use pins before that (like 50, 49, etc.) but those particular pins do not work (the program does not run, or freezes). I don't really have an option to switch pins because as of now I am using the others as digital inputs/outputs already. If anyone knows what my problem could be, please let me know. Thanks!