foo.cc: In function 'int main()':
foo.cc:53:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d %d",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~
foo.cc:56:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(i = 0;i<n;i++)scanf("%d",&a[i]);
                    ~~~~~^~~~~~~~~~~~
foo.cc:60:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d",&l,&r);
   ~~~~~^~~~~~~~~~~~~~

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