C:/mingw32/bin/../lib/gcc/i686-w64-mingw32/6.3.0/../../../../i686-w64-mingw32/lib/../lib/libmingw32.a(lib32_libmingw32_a-crt0_c.o):crt0_c.c:(.text.startup+0x39): undefined reference to `WinMain@16'
collect2.exe: error: ld returned 1 exit status