foo.cc: In function 'int main()':
foo.cc:8:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    8 |  scanf("%d",&n);
      |  ~~~~~^~~~~~~~~
foo.cc:9:29: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
    9 |  for(int i=1;i<=n;i++) scanf("%d%d",&a[i],&b[i]),v+=a[i]+b[i];
      |                        ~~~~~^~~~~~~~~~~~~~~~~~~~

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