import sys
input = sys.stdin.readline

N,K=list(map(int,input().split()))
A=list(map(int,input().split()))

if N<K*2-1:
    print("Impossible")
    exit()

DP=[[-1<<60]*(K+1) for i in range(N+3)]
DP[0][0]=0

for i in range(N):
    if i>=1:
        for j in range(K+1):
            DP[i][j]=max(DP[i][j],DP[i-1][j])

    for j in range(K-1,-1,-1):
        if DP[i][j]<=-1<<60:
            continue
        DP[i+2][j+1]=max(DP[i+2][j+1],DP[i][j]+A[i])

ANS=-1<<60

for i in range(N+3):
    ANS=max(ANS,DP[i][K])

print(ANS)