N,K=map(int,input().split())
A=list(map(int,input().split()))
tmp=1
sum_n=0
sum_b=sum(A)
for i in A[::-1]:
    sum_n+=tmp*i%sum_b
    tmp*=K
    tmp%=sum_b
    sum_n%=sum_b
print(sum_n%sum_b)