foo.cc: In function 'int main()':
foo.cc:28:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
  ~~~~~^~~~~~~~~~~~~~~~
foo.cc:33:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", &a[i][j]);
    ~~~~~^~~~~~~~~~~~~~~~
foo.cc:38:9: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    scanf("%d", &b[i][j]);
    ~~~~~^~~~~~~~~~~~~~~~
foo.cc:42:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d%d", &r, &c, &k);
  ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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