foo.cc: In function 'int main()':
foo.cc:16:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d%d", &n, &a[1], &k);
     ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:17:39: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for (int i = 2; i <= n; i++) scanf("%d", &a[i]);
                                  ~~~~~^~~~~~~~~~~~~

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