foo.cc: In function 'int main()':
foo.cc:6:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    6 |     scanf("%d",&n);//输入集合中总元素的数量
      |     ~~~~~^~~~~~~~~
foo.cc:11:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   11 |         scanf("%d",&a[i]);//输入集合中全部元素
      |         ~~~~~^~~~~~~~~~~~

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