foo.cc: In function 'int main()':
foo.cc:20:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=1;i<=n;i++)
              ~^~~
foo.cc:22:16: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'long long unsigned int*' [-Wformat=]
   scanf("%d",&x);
              ~~^
foo.cc:22:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&x);
   ~~~~~^~~~~~~~~

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