from collections.abc import Iterable
from enum import IntEnum, auto


def accum_dp(xs: Iterable, f, op, e, init: dict, *, is_reset=True):
    dp = init.copy()
    for x in xs:
        pp = {} if is_reset else dp.copy()
        dp, pp = pp, dp
        for fm_key, fm_val in pp.items():
            for to_key, to_val in f(fm_key, fm_val, x):
                dp[to_key] = op(dp.get(to_key, e), to_val)

    return dp


def op(a, b):
    return a + b


class E(IntEnum):
    S = 0,
    TAKE = auto()
    G = auto()


def f(k, v, x):
    s, b = k  # (状態, 0を含むか)
    match s:
        case E.S:  # まだ取ってない
            yield k, v
            # 取る
            nb = b | (x == 0)
            yield (E.TAKE, nb), v
        case E.TAKE:  # 取った
            nb = b | (x == 0)
            yield (E.TAKE, nb), v  # とり続ける

            # ここで終了
            if b:
                yield (E.G, b), v
        case E.G:  # 終了状態
            yield k, v
        case _:
            assert False


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

init = {(E.S, False): 1}
dp = accum_dp(A, f, op, 0, init)

ans = 0
for (t, b), v in dp.items():
    if t in [E.TAKE, E.G] and b:
        ans += v

print(ans)