n = int(input())
P = list(map(int,input().split()))
if 50 in P :
    print(0)
    exit()
b = 0
s = 0
for p in P:
    if p > 50:
        b += 1
    else:
        s += 1
if b == 0:
    print(0)
else:
    print(pow(2,n-1,10**9+7))