from itertools import cycle, chain
from math import inf


def calc_power_mod_loop(
        num: int, mod: int, digits: int = 1e6) -> tuple[list[int], int]:
    rests = [1]
    num_rest = num % mod
    power_num = num_rest
    ctr = 1
    while ctr < digits:
        try:
            exist_index = rests.index(power_num % mod)
            return rests, exist_index
        except ValueError:
            rests.append(power_num % mod)
            power_num *= num_rest
            ctr += 1
    return rests, -1


def main():
    N, K = map(int, input().split())
    digits = list(map(int, input().split()))
    digit_sum = sum(digits)

    K_rest = K % digit_sum

    rest = 0
    K_power = 1
    for digit in reversed(digits):
        rest += digit * K_power
        K_power = (K_power * K_rest) % digit_sum
    print(rest % digit_sum)


if __name__ == "__main__":
    main()