n, k = map(int, input().split())
plst = list(map(int, input().split()))
ans_double = k + sum(plst[:k])
total = ans_double
for i in range(n - k):
    total -= plst[i]
    total += plst[i + k]
    ans_double = max(ans_double, total)
print(ans_double / 2) n, k = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split k plst = list(map(int, input().split())) plst list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split ans_double = k + sum(plst[:k]) ans_double k + sum(plst[:k]) k sum(plst[:k]) sum plst[:k] plst :k k total = ans_double total ans_double for i in range(n - k):
    total -= plst[i]
    total += plst[i + k]
    ans_double = max(ans_double, total) i range(n - k) range n - k n k total -= plst[i] total plst[i] plst i total += plst[i + k] total plst[i + k] plst i + k i k ans_double = max(ans_double, total) ans_double max(ans_double, total) max ans_double total print(ans_double / 2) print ans_double / 2 ans_double 2 total += plst[i + k] plst[i + k] total total -= plst[i] plst[i] total ans_double = k + sum(plst[:k]) k + sum(plst[:k]) ans_double plst = list(map(int, input().split())) list(map(int, input().split())) plst total = ans_double ans_double total ans_double = max(ans_double, total) max(ans_double, total) ans_double k = map(int, input().split()) map(int, input().split()) k n, k = map(int, input().split()) map(int, input().split()) n
n, k = map(int, input().split())
plst = list(map(int, input().split()))
ans_double = k + sum(plst[:k])
total = ans_double
for i in range(n - k):
    total -= plst[i]
    total += plst[i + k]
    ans_double = max(ans_double, total)
print(ans_double / 2)