import re
import math


class SolveTask:
    def __init__(self):
        self._f = math.factorial

    def solve(*args, **kwargs):
        raise NotImplementedError

    def combinations(self, n, k):
        return self._f(n) // self._f(k) // self._f(n - k)

    def _parse_expression(self, expression):
        n = expression.split('^')[1]

        brakets = re.split('[()]', expression)

        values = list(map(lambda x: x.strip(), brakets[1].split('+')))
        values = [int(a) if '0' <= a <= '9' else a for a in values]

        return *values, int(n)

class Solve9a(SolveTask):
    def solve(self, n:int, m:int) -> int:
        return sum([(-1)**(m+i) * self.combinations(m, i) * i ** n for i in range(0, m+1)]) // self._f(m)


class Solve9b(SolveTask):
    def solve(self, n:int, m:int) -> int:
        return sum([(-1)**(m+i) * self.combinations(m, i) * i ** n for i in range(0, m+1)])