foo.cc: In function 'int main()':
foo.cc:23:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |     scanf("%d %d",&n,&m);
      |     ~~~~~^~~~~~~~~~~~~~~
foo.cc:28:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   28 |         scanf("%d %d",&v,&u);
      |         ~~~~~^~~~~~~~~~~~~~~

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