n = int(input())
a = list(map(int, input().split()))
ans = n * (n + 1) // 2
s = 0
for i in range(n):
    if a[i]:
        s += 1
    else:
        ans -= s * (s + 1) // 2
        s = 0
ans -= s * (s + 1) // 2
print(ans)