n, k = map(int, input().split())
digits = list(map(int, input().split()))
s = sum(digits)

pow_mod = [1] * n
for p in range(1, n):
    pow_mod[p] = (pow_mod[p-1] * k) % s

result = 0
for j in range(n):
    exponent_p = (n - 1) - j
    term = digits[j] * pow_mod[exponent_p]
    result = (result + term) % s

print(result)