N, K = map(int, input().split())
A = list(map(int, input().split()))
inf = 10**18
dp = [[-inf, -inf] for _ in range(K+1)]
ceil = lambda n, d: (n + d - 1) // d
if K > ceil(N, 2):
    print("Impossible")
    exit()
dp[0][0] = 0

for a in A:
    ndp = [[-inf, -inf] for _ in range(K+1)]
    for k in range(K+1):
        ndp[k][0] = max(ndp[k][0], dp[k][1], dp[k][0])
        if k+1 <= K:
            ndp[k+1][1] = max(ndp[k+1][1], dp[k][0]+a)

    dp = ndp

ans = max(dp[k][0], dp[k][1])
print(ans)