foo.cc: In function 'void init()':
foo.cc:20:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   20 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
foo.cc:23:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |         scanf("%d",&have[i]);
      |         ~~~~~^~~~~~~~~~~~~~~
foo.cc:26:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   26 |     scanf("%d",&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",&need[i]);
      |         ~~~~~^~~~~~~~~~~~~~~

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