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()

mod = sum(A)
digit = 1
ans = 0
for x in A:
    ans += (digit * x) % mod;
    digit = (digit * K) % mod;

print(ans)