#include <algorithm>
#include <list>
#include <execution>
#include <iterator>

auto merge_list(const std::list<int>& a, const std::list<int>& b) {
  std::list<int> o;
  std::merge(
    std::execution::seq,
    a.begin(),
    a.end(),
    b.begin(),
    b.end(),
    std::back_insert_iterator<std::list<int>>(o),
    [](const int a, const int b){
      return a < b;
    }
  );
  return o;
}

using System.Numerics;

public class basic 
{
		public static BigInteger pow(long down, ulong up)
		{
			BigInteger output = 1;
			BigInteger cumulativeDown = down;

			for(ulong bitChecker = 1; bitChecker > 0 && bitChecker <= up; bitChecker <<= 1)
			{
				if((bitChecker & up) != 0)
				{
					output *= cumulativeDown;
				}

				cumulativeDown *= cumulativeDown;
			}

			return output;
		}
}