foo.cc: In function 'int main()':
foo.cc:8:8: warning: unused variable 's' [-Wunused-variable]
    8 |  int n,s;scanf("%d",&n);
      |        ^
foo.cc:6:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    6 |  freopen("chiptest.in","r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:7:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    7 |  freopen("chiptest.out","w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:8:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    8 |  int n,s;scanf("%d",&n);
      |          ~~~~~^~~~~~~~~
foo.cc:11:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |    scanf("%d",&a[j][i]);
      |    ~~~~~^~~~~~~~~~~~~~~

Found 5 testcases.
[Hydro](https://hydro.ac)提供评测服务