foo.cc: In function 'int main()':
foo.cc:11:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
  ~~~~~^~~~~~~~~
foo.cc:13:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d%d%d",&a,&b,&g,&k);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:19:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&a,&b);
  ~~~~~^~~~~~~~~~~~~~

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