N,K = map(int,input().split())
A = list(map(int,input().split()))
Sum_A = sum(A)
Sum_K = sum(A[K:])
#Aの最小値をx
Pi = Sum_A - A[0]*N
Ri = sum(A[:K]) - A[0]*(K) #プラスのもの
Qi = Pi - Ri
ans = Pi - 2*Qi
#print(Pi,Qi,ans)

if K == 0:
    #Aの最大値をx
    PN = A[N-1]*N - sum(A)
    QN = A[N-1]*(N-K) - sum(A[:N-K])
    #print(PN,QN)
    ans = min(ans,PN-2*QN)
    print(ans);exit()

left = 0; right = K-1
for i in range(1,N):
    p_left = left; p_right = right
    d = A[i] - A[i-1]
    Ri+= d*(i - left) - d*(right - i + 1)
    while right < N-1 and abs(A[left] - A[i]) > abs(A[right+1] - A[i]):
        Ri -= abs(A[left] - A[i]) #大きくなった左を取り除く
        left += 1
        Ri += abs(A[right+1] - A[i]) #小さくなった右を加える
        right += 1
    #print(left,right,i)

    Pi += d*i - d*(N-i)
    Qi = Pi - Ri
    #print(Pi,Ri,Qi)
    temp = Pi - 2*Qi
    ans = min(ans,temp)
print(ans)