N, K = map(int, input().split())
p = [int(x) for x in input().split()]

ksum = [0 for _ in range(N-K+1)]
ksum[0] = sum(p[:K])
for i in range(N-K):
    ksum[i+1] = ksum[i] - p[i] + p[i+K]

print((K+max(ksum))/2) N, K = map(int, input().split()) N map(int, input().split()) map int input().split() ().split () input split K int(x) for x in input().split() for x in input().split() x input().split() ().split () input split for x in input().split() int(x) int x p = [int(x) for x in input().split()] p [int(x) for x in input().split()] 0 for _ in range(N-K+1) for _ in range(N-K+1) _ range(N-K+1) range N-K+1 N-K N K 1 for _ in range(N-K+1) 0 ksum = [0 for _ in range(N-K+1)] ksum [0 for _ in range(N-K+1)] ksum[0] = sum(p[:K]) ksum[0] ksum 0 sum(p[:K]) sum p[:K] p :K K for i in range(N-K):
    ksum[i+1] = ksum[i] - p[i] + p[i+K] i range(N-K) range N-K N K ksum[i+1] = ksum[i] - p[i] + p[i+K] ksum[i+1] ksum i+1 i 1 ksum[i] - p[i] + p[i+K] ksum[i] - p[i] ksum[i] ksum i p[i] p i p[i+K] p i+K i K print((K+max(ksum))/2) print (K+max(ksum))/2 K+max(ksum) K max(ksum) max ksum 2 ksum = [0 for _ in range(N-K+1)] [0 for _ in range(N-K+1)] ksum K = map(int, input().split()) map(int, input().split()) K N, K = map(int, input().split()) map(int, input().split()) N p = [int(x) for x in input().split()] [int(x) for x in input().split()] p
N, K = map(int, input().split())
p = [int(x) for x in input().split()]

ksum = [0 for _ in range(N-K+1)]
ksum[0] = sum(p[:K])
for i in range(N-K):
    ksum[i+1] = ksum[i] - p[i] + p[i+K]

print((K+max(ksum))/2)