foo.cc: In function 'int main()':
foo.cc:33:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d%d", &n, &m);
   ~~~~~^~~~~~~~~~~~~~~~
foo.cc:37:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
       scanf("%s", buf);
       ~~~~~^~~~~~~~~~~

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