foo.cc: In function 'int main()':
foo.cc:16:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%lld%lld",&n,&m);
  ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc:18:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%lld%lld%lld",&x,&y,&z);
   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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