foo.cc: In function 'int main()':
foo.cc:63:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   63 |  freopen("puzzling.in","r",stdin);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:64:9: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   64 |  freopen("puzzling.out","w",stdout);
      |  ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:65:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   65 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
foo.cc:68:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   68 |   scanf("%d%d\n",&a[i],&b[i]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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