foo.cc: In function 'int main()':
foo.cc:44:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld%lld",&a,&b);
     ~~~~~^~~~~~~~~~~~~~~~~~
foo.cc: In function 'long long int getans(long long int)':
foo.cc:14:35: warning: iteration 19 invokes undefined behavior [-Waggressive-loop-optimizations]
     for(int i=1;i<=20;i++)digit[i]=0;
                           ~~~~~~~~^~
foo.cc:14:18: note: within this loop
     for(int i=1;i<=20;i++)digit[i]=0;
                 ~^~~~

[Hydro](https://hydro.ac)提供评测服务