#region Header
#!/usr/bin/env python3
# from typing import *

import sys
import io
import math
import collections
import decimal
import itertools
from queue import PriorityQueue
import bisect
import heapq

def input():
    return sys.stdin.readline()[:-1]

sys.setrecursionlimit(1000000)
#endregion

# _INPUT = """# paste here...
# """
# sys.stdin = io.StringIO(_INPUT)

def main():
    N, K = map(int, input().split())
    A = list(map(int, input().split()))

    SumA = sum(A)
    A = sum((A[N-1-i] * pow(K, i, SumA)) % SumA for i in range(N))
    print(A % SumA)


if __name__ == '__main__':
    main()