foo.cc: In function 'int main()':
foo.cc:6:9: warning: zero-length gnu_printf format string [-Wformat-zero-length]
    6 |  printf("");
      |         ^~
foo.cc:8:9: warning: zero-length gnu_printf format string [-Wformat-zero-length]
    8 |  printf("", n);
      |         ^~
foo.cc:17:9: warning: too many arguments for format [-Wformat-extra-args]
   17 |  printf("%d\n", a[index], index);
      |         ^~~~~~
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    7 |  scanf("%d", &n);
      |  ~~~~~^~~~~~~~~~
foo.cc:11:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |   scanf("%d", &a[i]);
      |   ~~~~~^~~~~~~~~~~~~

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