/in/foo.c:1:1: warning: data definition has no type or storage class
    1 | n = int(input("请输入一个整数: "))
      | ^
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'n' [-Wimplicit-int]
/in/foo.c:1:5: error: expected expression before 'int'
    1 | n = int(input("请输入一个整数: "))
      |     ^~~