foo.cc: In function 'int main()':
foo.cc:10:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d",&m,&n);
     ~~~~~^~~~~~~~~~~~~~
foo.cc:12:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&a[i],&b[i]);
         ~~~~~^~~~~~~~~~~~~~~~~~~~

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