n = int(input())
A = list(map(int,input().split()))
cou = 0
r = 0
for i in range(n):
    if A[i] == 0:
        t = i - r + 1
        cou += t * (t-1) // 2
        r = i + 1
t = n - r + 1
cou += t * (t-1) // 2
print(n * (n+1) // 2 - cou)