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