foo.cc: In function 'int main()':
foo.cc:20:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
          scanf("%s" , str + 1) ;
          ~~~~~^~~~~~~~~~~~~~~~
foo.cc:43:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
                scanf("%s" , str + 1) ;
                ~~~~~^~~~~~~~~~~~~~~~

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