foo.cc: In function 'int main()':
foo.cc:15:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&n);
   ~~~~~^~~~~~~~~
foo.cc:18:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     while (scanf("%d",&x),x != 0)
            ~~~~~~~~~~~~~~^~~~~~~

[Hydro](https://hydro.ac)提供评测服务