foo.cc: In function 'int main()':
foo.cc:77:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&n,&m);
     ~~~~~^~~~~~~~~~~~~~
foo.cc:81:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d",w+i);
         ~~~~~^~~~~~~~~~
foo.cc:84:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&x,&y);
         ~~~~~^~~~~~~~~~~~~~

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