foo.cc: In function 'int main()':
foo.cc:14:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d", &n, &m, &k);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:15:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s", a);
  ~~~~~^~~~~~~~~
foo.cc:16:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s", b);
  ~~~~~^~~~~~~~~

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