import math
N, K = map(int,input().split())
li = list(map(int,input().split())) 
if(math.ceil(N / 2) < K):
    print("Impossible")
    exit()
dp = [[-5 * 10 ** 11] * (K + 1) for _ in range(N + 1)]

dp[0][0] = 0
for i in range(N):
    for j in range(K):
        if(dp[i][j] != -5 * 10 ** 11):
            dp[i + 1][j] = max(dp[i + 1][j], dp[i][j])
            dp[min(i + 2, N)][j + 1] = max(dp[min(i + 2, N)][j + 1], dp[i][j] + li[i])
print(dp[N][K])