foo.c:1:2: error: invalid preprocessing directive #\U000083b7\U000053d6\U00008f93\U00005165\U00007684\U00006b63\U000065b9\U00005f62\U00008fb9\U0000957f
    1 | #获取输入的正方形边长
      |  ^~~~~~~~~~~~~~~~~~~~
foo.c:2:1: warning: data definition has no type or storage class
    2 | a=int(input())
      | ^
foo.c:2:1: warning: type defaults to ‘int’ in declaration of ‘a’ [-Wimplicit-int]
foo.c:2:3: error: expected expression before ‘int’
    2 | a=int(input())
      |   ^~~
foo.c:3:2: error: invalid preprocessing directive #\U00008ba1\U00007b97\U00006b63\U000065b9\U00005f62\U00009762\U000079ef\U0000ff08\U00008fb9\U0000957f\U00007684\U00005e73\U000065b9\U0000ff09
    3 | #计算正方形面积（边长的平方）
      |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.c:5:2: error: invalid preprocessing directive #\U00008f93\U000051fa\U00009762\U000079ef
    5 | #输出面积
      |  ^~~~~~~~