foo.cc: In function 'int main()':
foo.cc:10:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     int n,m; scanf("%d%d", &n, &m);
              ~~~~~^~~~~~~~~~~~~~~~
foo.cc:13:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         int num; scanf("%d", &num);
                  ~~~~~^~~~~~~~~~~~

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