foo.cc: In function 'void Init()':
foo.cc:80:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   80 |  scanf("%d%d", &N, &M);
      |  ~~~~~^~~~~~~~~~~~~~~~
foo.cc:83:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   83 |   scanf("%d%d%d", &u, &v, &w);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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