N, K = map(int, input().split())
assert(1 <= N and N <= 100000)
assert(2 <= K and K <= 10000)

A = list(map(int, input().split()))
A.reverse()
assert(len(A) == N)
assert(A[N - 1] != 0)

mod = sum(A)
digit = 1
ans = 0

for x in A:
    assert(0 <= x and x < K)
    ans += digit * x
    ans %= mod
    digit *= K
    digit %= mod

print(ans)