n,k = map(int,input().split())
ns=list(map(int,input().split()))
nssum=sum(ns)

def  n_t(X,n):
    t = 0
    cnt=0
    for i in range(len(X)-1,-1,-1):
        t += X[cnt]*(n**i)
        cnt+=1
    return t
ns10 = n_t(ns,k)

print(ns10%nssum)