foo.cc: In function 'int main()':
foo.cc:72:29: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
         printf("%d ", ans[i]);
                       ~~~~~~^
foo.cc:60:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld%lld", &a, &b);
     ~~~~~^~~~~~~~~~~~~~~~~~~~

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