N, K, *X = map(int, open(0).read().split())

y = [float(x * (x + 1) / 2 / x) for x in X]
ans = sum(y[:K])
res = ans
for i in range(K, N):
    res = res - y[i - K] + y[i]
    ans = max(ans, res)
print(ans) N, K, *X = map(int, open(0).read().split()) N map(int, open(0).read().split()) map int open(0).read().split() (0).read().split (0).read() (0).read (0) open 0 read split K *X X float(x * (x + 1) / 2 / x) for x in X for x in X x X for x in X float(x * (x + 1) / 2 / x) float x * (x + 1) / 2 / x x * (x + 1) / 2 x * (x + 1) x x + 1 x 1 2 x y = [float(x * (x + 1) / 2 / x) for x in X] y [float(x * (x + 1) / 2 / x) for x in X] ans = sum(y[:K]) ans sum(y[:K]) sum y[:K] y :K K res = ans res ans for i in range(K, N):
    res = res - y[i - K] + y[i]
    ans = max(ans, res) i range(K, N) range K N res = res - y[i - K] + y[i] res res - y[i - K] + y[i] res - y[i - K] res y[i - K] y i - K i K y[i] y i ans = max(ans, res) ans max(ans, res) max ans res print(ans) print ans ans = max(ans, res) max(ans, res) ans K, *X = map(int, open(0).read().split()) map(int, open(0).read().split()) K N, K, *X = map(int, open(0).read().split()) map(int, open(0).read().split()) N y = [float(x * (x + 1) / 2 / x) for x in X] [float(x * (x + 1) / 2 / x) for x in X] y res = res - y[i - K] + y[i] res - y[i - K] + y[i] res res = ans ans res ans = sum(y[:K]) sum(y[:K]) ans
N, K, *X = map(int, open(0).read().split())

y = [float(x * (x + 1) / 2 / x) for x in X]
ans = sum(y[:K])
res = ans
for i in range(K, N):
    res = res - y[i - K] + y[i]
    ans = max(ans, res)
print(ans)
