foo.cc: In function 'void dts::main()':
foo.cc:54:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",&n);
         ~~~~~^~~~~~~~~
foo.cc:56:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d",&a[i]),num[i]=i;
             ~~~~~~~~~~~~~~~~~^~~~~~~~~

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