n,k = map(int,input().split())
a = list(map(int,input().split()))

k = n-k

ans = 10**15

b = [1]*(n-k)+[-1]*k
ruiseki = [0]*(n+1)
for i in range(n):
    ruiseki[i+1] = ruiseki[i]+b[i]
base = 0
while base+1 < n and ruiseki[base+1] < (n-2*k+1)//2:
    base += 1
left = sum(a[i]-a[base] for i in range(n-k))+sum(a[base]-a[i] for i in range(n-k,n))

b = [-1]*k+[1]*(n-k)
ruiseki = [0]*(n+1)
for i in range(n):
    ruiseki[i+1] = ruiseki[i]+b[i]
base = n-1
while 0 < base and ruiseki[n]-ruiseki[base] < (n-2*k+1)//2:
    base -= 1
right = sum(a[i]-a[base] for i in range(k))+sum(a[base]-a[i] for i in range(k,n))

ans = min(ans,left,right)
print(ans)