import sys
input = lambda : sys.stdin.readline().rstrip()

sys.setrecursionlimit(2*10**5+10)
write = lambda x: sys.stdout.write(x+"\n")

n,k = list(map(int, input().split()))
a = list(map(int, input().split()))
cum = [0]
v = 0
for i in range(n):
    v += a[i]
    cum.append(v)
l = 0
ans = float("inf")
for i in range(n):
    x = a[i]
    while l<i and l<n-k and x - a[l] > a[k+l] - x:
        l += 1
    val = cum[l] - (cum[i] - cum[l]) + (cum[k+l] - cum[i]) - (cum[n] - cum[k+l])
    ans = min(ans, val + x * (n - 2*k - 4*l + 2*i))
#     print(i,l,val,x * (n - 2*k - 4*l + 2*i))
print(ans)