foo.cc: In function 'int main()':
foo.cc:20:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   20 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
foo.cc:24:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   24 |   scanf("%d",&n);
      |   ~~~~~^~~~~~~~~

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