/in/foo.c:1:1: warning: data definition has no type or storage class
    1 | a=int(input("正方形花坛边长"))
      | ^
/in/foo.c:1:1: warning: type defaults to 'int' in declaration of 'a' [-Wimplicit-int]
/in/foo.c:1:3: error: expected expression before 'int'
    1 | a=int(input("正方形花坛边长"))
      |   ^~~