/in/foo.cc: In function 'int main()':
/in/foo.cc:11:16: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d",&n);
                ^
/in/foo.cc:15:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
      scanf("%d %d",&h[i],&v[i]);
                                ^