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

p,q = 0,0
for i in range(N):
    if P[i]>50:
        p += 1
    elif P[i]<50:
        q += 1

fac = [0]*(p+1)
inv = [0]*(p+1)
fac[0]=inv[0]=1
for i in range(1,p+1):
    fac[i] = (fac[i-1]*i)%mod
    inv[i] = (inv[i-1]*pow(i,mod-2,mod))%mod
res = 0
P = p
po = pow(2,q,mod)
while p>0:
    if p%2==0:
        p -= 1
    else:
        res += (fac[P]*inv[p]*inv[P-p]*po)%mod
        res %= mod
        p -= 1
print(res)