Hi!
One of the C++ programmers problems is to work with integers greater than 2^64-1 (we can save 0to 2^64-1 in unsigned long long int). So I want to share the best Bignum implementation I have ever seen (Link) with CodeForces Community.
Its specifications are as follows:
Supported operations:
+,-,/,*,%,^(pow) ,gcd,lcm,abs.It is able to work with Standard Input/Output streams.
It can cast data to
long long,string.It uses fast multiplication.



