game.cpp:17:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type]
main()
^
/tmp/ccyjUBa2.o: In function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'
/tmp/ccP1PUGw.o:game.cpp:(.text.startup+0x0): first defined here
/tmp/ccP1PUGw.o: In function `main':
game.cpp:(.text.startup+0xb): undefined reference to `initialize(int)'
/tmp/ccyjUBa2.o: In function `main':
grader.cpp:(.text.startup+0x14): undefined reference to `initialize(int)'
collect2: error: ld returned 1 exit status