Owl Get a Life

Compile Error

/usr/bin/ld: /usr/lib/gcc/x86_64-linux-gnu/9/../../../x86_64-linux-gnu/crt1.o: in function `_start':
(.text+0x24): undefined reference to `main'
/usr/bin/ld: /tmp/cckGEd9m.o: in function `std::_Function_handler<void (), determine_type(int)::{lambda()#1}>::_M_invoke(std::_Any_data const&)':
shops.cpp:(.text+0x155): undefined reference to `query_machine(std::vector<int, std::allocator<int> >)'
/usr/bin/ld: /tmp/cckGEd9m.o: in function `determine_type(int)':
shops.cpp:(.text+0x481): undefined reference to `query_machine(std::vector<int, std::allocator<int> >)'
/usr/bin/ld: shops.cpp:(.text+0x7ef): undefined reference to `answer_type(std::vector<char, std::allocator<char> >)'
/usr/bin/ld: shops.cpp:(.text+0xa07): undefined reference to `query_machine(std::vector<int, std::allocator<int> >)'
/usr/bin/ld: shops.cpp:(.text+0xbb9): undefined reference to `query_machine(std::vector<int, std::allocator<int> &g