import sys
import math
import bisect
import heapq
from collections import deque, defaultdict 
#160427717982164055zq
# -------------------------------------------------
def ST(): return input().rstrip()
def IN(): return int(input())
def ML(typ=int): return [typ(x) for x in input().split()]
def IM(): return ML()
def IL(): return ML()
def SR(n:int)->list: return [input().rstrip() for _ in range(n)]
def IMatrix(n:int)->list: return [Mul(int) for _ in range(n)]

def prefix_sum(L): #1次元リストの累積和を返す
    ret = [L[0]]
    for i in range(1, len(L)):
        ret.append(ret[i-1]+L[i])
    return ret
    
N, K = IM()
A = IL()
if N//2 < K:
    print("Impossible")
    exit()
    
dp = [[-10**17]*(K+1) for _ in range(N+1)] # A[:i]のうちちょうどj個を削除したときの最大値。不可能な操作は負の無限大
dp[0][0] = 0

for i in range(1, N+1):
    for j in range(K+1):
        if j == 0:
            dp[i][j] = 0
        elif j == 1:
            dp[i][j] = max(dp[i][j], dp[i-1][j], dp[i-1][j-1]+A[i-1])
        else:
            dp[i][j] = max(dp[i][j], dp[i-1][j], dp[i-2][j-1]+A[i-1])

print(dp[N][K])
#for i in dp:
#    print(i)