foo.cc: In function 'void in()':
foo.cc:24:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d%d%d%d", &N, &K, &H, &R);
 ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:26:6: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
 scanf("%d%d", &a, &b);
 ~~~~~^~~~~~~~~~~~~~~~

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