n = int(input())
P = list(map(int, input().split()))
mod = 10**9 + 7

over_fifty = 0
less_fifty = 0
for i in range(n):
    if P[i] > 50:
        over_fifty += 1
    elif P[i] < 50:
        less_fifty += 1
if over_fifty == 0:
    print(0)
else:
    print(pow(2, over_fifty + less_fifty - 1, mod))