/usr/bin/ld: /tmp/cconyFzm.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccWvf4yj.o:vision.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/cconyFzm.o: in function `add_and(std::vector<int, std::allocator<int> >)':
grader.cpp:(.text+0x150): multiple definition of `add_and(std::vector<int, std::allocator<int> >)'; /tmp/ccWvf4yj.o:vision.cpp:(.text+0x320): first defined here
/usr/bin/ld: /tmp/cconyFzm.o: in function `add_or(std::vector<int, std::allocator<int> >)':
grader.cpp:(.text+0x170): multiple definition of `add_or(std::vector<int, std::allocator<int> >)'; /tmp/ccWvf4yj.o:vision.cpp:(.text+0x340): first defined here
/usr/bin/ld: /tmp/cconyFzm.o: in function `add_xor(std::vector<int, std::allocator<int> >)':
grader.cpp:(.text+0x190): multiple definition of `add_xor(std::vector<int, std::allocator<int> >)'; /tmp/ccWvf4yj.o:vision.cpp:(.text+0x360): first defined here
/usr/bin/ld: /tmp/cconyFzm.o: in function `add_not(int)':
grader.cpp:(.text+0x1b0): multiple definition of `add_not(int)'; /tmp/ccWvf4yj.o:vision.cpp:(.text+0x380): first defined here
collect2: error: ld returned 1 exit status