foo.cc: In function 'int main()':
foo.cc:6:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    6 |  int m, n; scanf("%d%d", &m, &n);
      |            ~~~~~^~~~~~~~~~~~~~~~
foo.cc:9:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |   scanf("%d", &a[i]);
      |   ~~~~~^~~~~~~~~~~~~

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