N, K = map(int, input().split())
P = list(map(int, input().split()))
P = [(1+p)/2 for p in P]
L = [0]*(N+1)
for i in range(N):
  L[i+1] = L[i]+P[i]
print(max(L[i+K]-L[i] for i in range(N-K+1))) N, K = map(int, input().split()) N map(int, input().split()) map int input().split() ().split () input split K P = list(map(int, input().split())) P list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split (1+p)/2 for p in P for p in P p P for p in P (1+p)/2 1+p 1 p 2 P = [(1+p)/2 for p in P] P [(1+p)/2 for p in P] L = [0]*(N+1) L [0]*(N+1) [0] 0 N+1 N 1 for i in range(N):
  L[i+1] = L[i]+P[i] i range(N) range N L[i+1] = L[i]+P[i] L[i+1] L i+1 i 1 L[i]+P[i] L[i] L i P[i] P i print(max(L[i+K]-L[i] for i in range(N-K+1))) print max(L[i+K]-L[i] for i in range(N-K+1)) max L[i+K]-L[i] L[i+K] L i+K i K L[i] L i K = map(int, input().split()) map(int, input().split()) K P = list(map(int, input().split())) list(map(int, input().split())) P N, K = map(int, input().split()) map(int, input().split()) N L = [0]*(N+1) [0]*(N+1) L P = [(1+p)/2 for p in P] [(1+p)/2 for p in P] P
N, K = map(int, input().split())
P = list(map(int, input().split()))
P = [(1+p)/2 for p in P]
L = [0]*(N+1)
for i in range(N):
  L[i+1] = L[i]+P[i]
print(max(L[i+K]-L[i] for i in range(N-K+1)))