def main():
    import sys
    input = sys.stdin.read
    data = input().split()
    
    N = int(data[0])
    K = int(data[1])
    A = list(map(int, data[2:2+N]))
    
    pre_sum = [0] * (N + 1)
    for i in range(1, N + 1):
        pre_sum[i] = pre_sum[i - 1] + A[i - 1]
    
    min_f = float('inf')
    
    for i in range(N):
        current_A = A[i]
        if K == 0:
            sum_k = 0
        else:
            sum_k = 0
            if K >= 1:
                m = min(K - 1, i)
                n = K - 1 - m
                if n > (N - 1 - i):
                    n = N - 1 - i
                    m = K - 1 - n
                sum_left = 0
                if m > 0:
                    if i - m >= 0:
                        sum_left = current_A * m - (pre_sum[i] - pre_sum[i - m])
                sum_right = 0
                if n > 0:
                    if i + n < N:
                        sum_right = (pre_sum[i + n + 1] - pre_sum[i + 1]) - current_A * n
                sum_k += sum_left + sum_right
        
        left_sum = current_A * i - pre_sum[i]
        right_sum = (pre_sum[N] - pre_sum[i + 1]) - current_A * (N - 1 - i)
        S = left_sum + right_sum
        
        f = 2 * sum_k - S
        if f < min_f:
            min_f = f
    
    print(min_f)

if __name__ == "__main__":
    main()