N,K=map(int,input().split())
A=list(map(int,input().split()))
if K>(N+1)//2:
    print('Impossible')
    exit()

INF=-10**18
dp=[[INF]*(K+1) for i in range(N+1)]
dp[0][0]=0
dp[1][1]=A[0]
for i in range(1,N+1):
    for j in range(K+1):
        dp[i][j]=max(dp[i][j],dp[i-1][j])
        if i>=2 and j>=1:
            dp[i][j]=max(dp[i][j],dp[i-2][j-1]+A[i-1])

print(dp[-1][K])