foo.cc: In function 'int main()':
foo.cc:8:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    8 |  scanf("%lld%lld", &n, &m);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~
foo.cc:12:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   12 |   scanf("%lld%lld", &x, &y);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~

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