n = int(input())
A = list(map(int, input().split()))

ans = n * (n - 1) // 2 + n
cnt = 0
for i in range(n):
    if A[i] == 1:
        cnt += 1
        if i == n - 1:
            ans -= cnt * (cnt - 1) // 2 + cnt
    else:
        ans -= cnt * (cnt - 1) // 2 + cnt
        cnt = 0
print(ans)