foo.cc: In function 'void init()':
foo.cc:14:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);     n++;
     ~~~~~^~~~~~~~~
foo.cc:15:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&m);
     ~~~~~^~~~~~~~~
foo.cc:18:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&x,&y,&w);
         ~~~~~^~~~~~~~~~~~~~~~~~~

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