foo.cc: In function 'int main()':
foo.cc:10:9: warning: zero-length gnu_printf format string [-Wformat-zero-length]
   10 |  printf("");
      |         ^~
foo.cc:5:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    5 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~

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