CCF python 跳一跳

list1 = []
list1 = list(map(int, input().split()))
k = 1
num = 0
for i in list1:
    if i == 1:
        num = num + 1
        k = 1
    elif i == 2:
        num = num + 2 * k
        k = k + 1
print(num)