/in/foo.c:1:1: warning: data definition has no type or storage class
    1 | num = int(input("请输入一个整数: "))
      | ^~~
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'num' [-Wimplicit-int]
/in/foo.c:1:7: error: expected expression before 'int'
    1 | num = int(input("请输入一个整数: "))
      |       ^~~