from collections import deque, defaultdict, Counter
from bisect import bisect_left, bisect_right, insort
from itertools import permutations, combinations, groupby
from heapq import heappop, heappush
import math, sys
input = lambda: sys.stdin.readline().rstrip("\r\n")
def printl(li, sep=" "): print(sep.join(map(str, li)))
def yn(flag): print(Yes if flag else No)
_int = lambda x: int(x)-1
MOD = 998244353 #10**9+7
INF = 1<<60
Yes, No = "Yes", "No"

N, K = map(int, input().split())
A = list(map(int, input().split()))
if (N+1)//2 < K:
    print("Impossible")
    exit()
dp = [-INF]*(K+1)*2
def ind(i, t): return i*2+t
dp[ind(0, 0)] = 0
for a in A:
    ndp = [-INF]*(K+1)*2
    for k in range(K+1):
        ndp[ind(k, 0)] = max(dp[ind(k, 0)], dp[ind(k, 1)])
        if k == K: break
        ndp[ind(k+1, 1)] = dp[ind(k, 0)]+a
    dp = ndp[:]
ans = max(dp[ind(K, 0)], dp[ind(K, 1)])
print(ans)