foo.cc: In function 'int main()':
foo.cc:80:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &n, &m);
     ~~~~~^~~~~~~~~~~~~~~~
foo.cc:82:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld", &num[i]);
         ~~~~~^~~~~~~~~~~~~~~~~
foo.cc:87:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &opt);
         ~~~~~^~~~~~~~~~~~
foo.cc:91:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d%d%lld", &x, &y, &val);
             ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
foo.cc:95:18: 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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