n, k = map(int, input().split())
k = n - k
a = list(map(int, input().split()))
now = sum(x - a[0] for x in a[:n - k]) - sum(x - a[0] for x in a[n - k: n])
ans = now
l = 0
r = n - k
for i in range(1, n):
    x = a[i]
    now += (a[i] - a[i-1]) * (-l + i-l - (r-i) + n-r)
    while l < i and r < n and x - a[l] > a[r] - x:
        now += -2 * (x - a[l]) + 2 * (a[r] - x)
        l += 1
        r += 1
    ans = min(ans, now)
print(ans)