/in/foo.c:1:1: error: unknown type name 'def'
    1 | def find_perfect_numbers():
      | ^~~
/in/foo.c: In function 'find_perfect_numbers':
/in/foo.c:1:27: error: expected declaration specifiers before ':' token
    1 | def find_perfect_numbers():
      |                           ^
/in/foo.c:16:14: error: stray '#' in program
   16 |     print()  # 换行
      |              ^
/in/foo.c:19: warning: control reaches end of non-void function [-Wreturn-type]