ans = 10 ** 18
n, k = map(int, input().split())
a = list(map(int, input().split()))
b = [1] * k + [-1] * (n - k)
x = a[0]
ans = min(ans, sum(b[i] * abs(x - a[i]) for i in range(n)))
x = a[-1]
ans = min(ans, sum(b[i] * abs(x - a[i]) for i in range(n)))
b = [-1] * (n - k) + [1] * k
x = a[0]
ans = min(ans, sum(b[i] * abs(x - a[i]) for i in range(n)))
x = a[-1]
ans = min(ans, sum(b[i] * abs(x - a[i]) for i in range(n)))
print(ans)