/tmp/ccMhvB45.o: In function `query(int, int)':
grader.cpp:(.text+0x0): multiple definition of `query(int, int)'
/tmp/cc9mLFDe.o:xylophone.cpp:(.text+0x0): first defined here
/tmp/ccMhvB45.o: In function `answer(int, int)':
grader.cpp:(.text+0x90): multiple definition of `answer(int, int)'
/tmp/cc9mLFDe.o:xylophone.cpp:(.text+0xa0): first defined here
/tmp/ccMhvB45.o: In function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'
/tmp/cc9mLFDe.o:xylophone.cpp:(.text.startup+0x0): first defined here
/tmp/cc9mLFDe.o: In function `main':
xylophone.cpp:(.text.startup+0x7c): undefined reference to `solve(int)'
/tmp/ccMhvB45.o: In function `main':
grader.cpp:(.text.startup+0x2c): undefined reference to `solve(int)'
collect2: error: ld returned 1 exit status