def getCost(ON, C, K):
    # print(ON)
    if sum(ON) == 0:
        return 0
    costs = []
    for n in range(len(ON)):
        if ON[n] == 1:
            NEW = ON[:]
            for a in range(-K, K+1):
                if n+a > -1 and n+a < len(ON):
                    NEW[n+a] = 0
            costs.append(C[n] + getCost(NEW, C, K))
    return min(costs)
                
N, K = [int(n) for n in input().split()]
C = [int(n) for n in input().split()]
ON = [1]*N
print(getCost(ON, C, K))