n = int(input())
C = list(map(int, input().split()))
A = []
for i, c in enumerate(C, 1):
    A += [i] * c
memo = {}


def f(bit, tot, t, x, ten):
    if tot % x != 0:
        return 0
    if t == n:
        return (tot & -tot).bit_length() - 1

    tmp = tot * n + t
    if tmp in memo:
        return memo[tmp]

    ret = t
    for i in range(n):
        if not bit >> i & 1:
            if i > 0 and A[i - 1] == A[i] and not (bit >> (i - 1) & 1):
                continue
            ret = max(ret, f(bit ^ (1 << i), A[i] * ten + tot, t + 1, x * 2, ten * 10))

    memo[tmp] = ret
    return ret


ans = f(0, 0, 0, 1, 1)
print(ans)