/usr/bin/ld: /tmp/ccP3AabN.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccSBcQ5M.o:catdog.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccP3AabN.o: in function `main':
grader.cpp:(.text.startup+0x1e2): undefined reference to `initialize(int, std::vector<int, std::allocator<int> >, std::vector<int, std::allocator<int> >)'
/usr/bin/ld: grader.cpp:(.text.startup+0x219): undefined reference to `neighbor(int)'
/usr/bin/ld: grader.cpp:(.text.startup+0x25e): undefined reference to `dog(int)'
/usr/bin/ld: grader.cpp:(.text.startup+0x269): undefined reference to `cat(int)'
collect2: error: ld returned 1 exit status