N, K = [int(s) for s in input().split(' ')]
P = [int(s) for s in input().split(' ')]
s = []
a = sum(P[0:K])
s.append(a)
for p0, p1 in zip(P, P[K:]):
    a = a - p0 + p1
    s.append(a)

print((max(s) + K) / 2) int(s) for s in input().split(' ') for s in input().split(' ') s input().split(' ') ().split () input split ' ' for s in input().split(' ') int(s) int s N, K = [int(s) for s in input().split(' ')] N [int(s) for s in input().split(' ')] K int(s) for s in input().split(' ') for s in input().split(' ') s input().split(' ') ().split () input split ' ' for s in input().split(' ') int(s) int s P = [int(s) for s in input().split(' ')] P [int(s) for s in input().split(' ')] s = [] s [] a = sum(P[0:K]) a sum(P[0:K]) sum P[0:K] P 0:K 0 K s.append(a) s.append s append a for p0, p1 in zip(P, P[K:]):
    a = a - p0 + p1
    s.append(a) p0 p1 zip(P, P[K:]) zip P P[K:] P K: K a = a - p0 + p1 a a - p0 + p1 a - p0 a p0 p1 s.append(a) s.append s append a print((max(s) + K) / 2) print (max(s) + K) / 2 max(s) + K max(s) max s K 2 s = [] [] s K = [int(s) for s in input().split(' ')] [int(s) for s in input().split(' ')] K P = [int(s) for s in input().split(' ')] [int(s) for s in input().split(' ')] P a = sum(P[0:K]) sum(P[0:K]) a N, K = [int(s) for s in input().split(' ')] [int(s) for s in input().split(' ')] N a = a - p0 + p1 a - p0 + p1 a
N, K = [int(s) for s in input().split(' ')]
P = [int(s) for s in input().split(' ')]
s = []
a = sum(P[0:K])
s.append(a)
for p0, p1 in zip(P, P[K:]):
    a = a - p0 + p1
    s.append(a)

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