foo.cc: In function 'int main()':
foo.cc:19:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   19 |     freopen("sortt.in","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:20:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   20 |     freopen("sortt.out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:22:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   22 |     scanf("%d",&n);
      |     ~~~~~^~~~~~~~~
foo.cc:23:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   23 |     for(int i=1;i<=n;i++)  scanf("%lf",&a[i]);
      |                            ~~~~~^~~~~~~~~~~~~

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