# Enter your code here. Read input from STDIN. Print output to STDOUT


def get_i(arr):
    for i in range(n):
        if sum(arr[i-k:i+k+1]) == 2*k:
            return i

        
def df(arr):
    for i in range(n):
        if sum(arr) == sum(arr[i-k:i+k+1]):
            return cost[i]
    mins = []
    for i in range(n):
        tarr = arr[:i-k] + [0 for tpi in range(2*k)] + arr[i+k:]
        mins.append(df(tarr) + cost[i])
    return min(mins)
        
n,k = map(int, raw_input().split())
cost = map(int, raw_input().split())
arr = [1 for _ in range(n)]
print df(arr)