foo.cc: In function 'int main()':
foo.cc:25:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&n);
     ~~~~~^~~~~~~~~~~
foo.cc:28:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld %lld",a+i,b+i);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~

[Hydro](https://hydro.ac)提供评测服务