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

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