foo.cc: In function 'int main()':
foo.cc:14:12: warning: unused variable 'x' [-Wunused-variable]
   14 |  long long x;
      |            ^
foo.cc:17:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |   scanf("%lld", &a[i]);
      |   ~~~~~^~~~~~~~~~~~~~~

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