rt

//倍增高精除
Bignum operator/(const Bignum &a1,const Bignum &b1){
        Bignum cp=1,a=a1,b=b1,s;
        while(a>=b) b=b<<1,cp=cp<<1;
        while(cp.len!=0){
            if(a>=b) a=a-b,s=s+cp;
            b=b>>1,cp=cp>>1;
        }
        return s;
    }
/*
>= O(n)
<< O(n)
>> O(n)
- O(n)
+ O(n)
*/