foo.cc: In function 'int main()':
foo.cc:19:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&k);
     ~~~~~^~~~~~~~~
foo.cc:24:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d\n%d\n",&n,&who);
         ~~~~~^~~~~~~~~~~~~~~~~~~~
foo.cc:27:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d",&a);
             ~~~~~^~~~~~~~~

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