foo.cc: In function 'int main()':
foo.cc:31:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &N);
  ~~~~~^~~~~~~~~~
foo.cc:32:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(int i=1;i<=N;++i) scanf("%d%d", &A[i], &B[i]);
                        ~~~~~^~~~~~~~~~~~~~~~~~~~~~

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