foo.cc: In function 'int main()':
foo.cc:41:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
foo.cc:43:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%s",s);
   ~~~~~^~~~~~~~
foo.cc:48:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d%d",&a,&b,&c,&d);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

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