foo.cc: In function 'int main()':
foo.cc:10:25: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'int (*)[505]' [-Wformat=]
    scanf("%d", a + i + j);
                ~~~~~~~~~^
foo.cc:17:36: error: expected ';' before ']' token
     second = first, first = a[i][j]];
                                    ^
foo.cc:25:1: error: expected '}' at end of input
 }
 ^
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &n);
  ~~~~~^~~~~~~~~~
foo.cc:10:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", a + i + j);
    ~~~~~^~~~~~~~~~~~~~~~~

自豪的采用 HydroJudger 进行评测(github.com/hydro-dev/HydroJudger)