from heapq import heapify, heappop, heappush
N,K=map(int,input().split())
A=list(map(int,input().split()))
if N%2==1 and N//2+1<K:
    print("Impossible")
elif N%2==0 and N//2<K:
    print("Impossible")
else:
    EA=list(map(list,sorted(enumerate(A),key=lambda x: x[1],reverse=True)))
    ANS=0
    ANS+=EA[0][1]
    T=EA[0][0]
    CNT=1
    for i in range(1,N):
        if abs(T-EA[i][0])>1:
            CNT+=1
            T=EA[i][0]
            ANS+=EA[i][1]
            if CNT==K:
                break
    if CNT==K:
        print(ANS)
    else:
        print("Impossible")