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

le = [(p + 1) / 2 for p in lp]

e = sum(le[:k])
m = e
for i in range(n - k):
    e -= le[i]
    e += le[k + i]
    m = max(m, e)

print(m) n, k = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split k lp = list(map(int, input().split())) lp list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split (p + 1) / 2 for p in lp for p in lp p lp for p in lp (p + 1) / 2 p + 1 p 1 2 le = [(p + 1) / 2 for p in lp] le [(p + 1) / 2 for p in lp] e = sum(le[:k]) e sum(le[:k]) sum le[:k] le :k k m = e m e for i in range(n - k):
    e -= le[i]
    e += le[k + i]
    m = max(m, e) i range(n - k) range n - k n k e -= le[i] e le[i] le i e += le[k + i] e le[k + i] le k + i k i m = max(m, e) m max(m, e) max m e print(m) print m le = [(p + 1) / 2 for p in lp] [(p + 1) / 2 for p in lp] le lp = list(map(int, input().split())) list(map(int, input().split())) lp e += le[k + i] le[k + i] e n, k = map(int, input().split()) map(int, input().split()) n e = sum(le[:k]) sum(le[:k]) e k = map(int, input().split()) map(int, input().split()) k m = e e m e -= le[i] le[i] e m = max(m, e) max(m, e) m
n, k = map(int, input().split())
lp = list(map(int, input().split()))

le = [(p + 1) / 2 for p in lp]

e = sum(le[:k])
m = e
for i in range(n - k):
    e -= le[i]
    e += le[k + i]
    m = max(m, e)

print(m)
