n,k = map(int,input().split())
A = list(map(int,input().split()))
k -= 1
if A[k]<=0:
    print(A[k])
else:
    l,r = k-1, k+1
    cl,cr = 0,0
    while l>=0:
        if A[l]!=0 and A[l]%2==0:
            cl += A[l]
        elif A[l]%2!=0:
            cl += A[l]
            break
        elif A[l]==0:
            break
        l -= 1
    
    while r<n:
        if A[r]!=0 and A[r]%2==0:
            cr += A[r]
        elif A[r]%2!=0:
            cr += A[r]
            break
        elif A[r]==0:
            break
        r += 1
    
    print(cl+cr+A[k])