foo.cc: In function 'int main()':
foo.cc:5:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    5 |     freopen("area.in","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
foo.cc:6:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
    6 |     freopen("area.out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
foo.cc:10:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   10 |          scanf("%d",&a[i][j]);
      |          ~~~~~^~~~~~~~~~~~~~~

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