N,K=map(int,input().split())
P=list(map(int,input().split()))
from itertools import accumulate
acc=[0]+list(accumulate(P))
print((max(b-a for a,b in zip(acc,acc[K:]))+K)/2) 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 from itertools import accumulate acc=[0]+list(accumulate(P)) acc [0]+list(accumulate(P)) [0] 0 list(accumulate(P)) list accumulate(P) accumulate P print((max(b-a for a,b in zip(acc,acc[K:]))+K)/2) print (max(b-a for a,b in zip(acc,acc[K:]))+K)/2 max(b-a for a,b in zip(acc,acc[K:]))+K max(b-a for a,b in zip(acc,acc[K:])) max b-a b a K 2 acc=[0]+list(accumulate(P)) [0]+list(accumulate(P)) acc N,K=map(int,input().split()) map(int,input().split()) N 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())
P=list(map(int,input().split()))
from itertools import accumulate
acc=[0]+list(accumulate(P))
print((max(b-a for a,b in zip(acc,acc[K:]))+K)/2)