These two files need a main$()$ to run their functions countWithList$()$ and countWithTree$().$ Then all three C files need a header file to inform them of what the others have that they need. Please finish both the main$()$ and header.h$.$

Please note! Not everything needs to be shared.

main$()$ needs countWithList$()$ and countWithTree$()$

Both countWithList$()$ and countWithTree$()$ need getNextNumber$().$

Otherwise, it is best not to share too much, kind of like keeping methods and members private in C$++$ and Java.