foo.cc: In function 'void solve3()':
foo.cc:65:37: 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("%lld ",a+i);
                                ~~~~~^~~~~~~~~~~~~
foo.cc:66:37: 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("%lld ",b+i);
                                ~~~~~^~~~~~~~~~~~~

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。