N = int(input())
A = list(map(int, input().split())) + [0]
Len, Ans = 0, N * (N + 1) // 2
for i in range(N + 1):
    if A[i] == 0:
        Ans -= Len * (Len + 1) // 2
        Len = 0
    else:
        Len += 1
print(Ans)