sales = [10, 20, 30, 10, 40, 20]
k = 3
answer = 0
idx = 0

for i in range(len(sales)-k):
    if sales[i] + sales[i+1] + sales[i+2] > answer:
        answer = sales[i] + sales[i+1] + sales[i+2]
        idx = i

print(answer)