foo.cc: In function 'int main()':
foo.cc:21:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   21 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
foo.cc:22:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   22 |     for (int i = 1; i <= n; ++i) scanf("%d", a + i);
      |                                  ~~~~~^~~~~~~~~~~~~
foo.cc:25:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   25 |     scanf("%d", &m);
      |     ~~~~~^~~~~~~~~~
foo.cc:28:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   28 |         scanf("%d%d", &l, &r);
      |         ~~~~~^~~~~~~~~~~~~~~~

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