import sys

sys.setrecursionlimit(10**7)
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int,sys.stdin.readline().rstrip().split())
def LI(): return list(map(int,sys.stdin.readline().rstrip().split()))
def LI2(): return list(map(int,sys.stdin.readline().rstrip()))
def S(): return sys.stdin.readline().rstrip()
def LS(): return list(sys.stdin.readline().rstrip().split())
def LS2(): return list(sys.stdin.readline().rstrip())


def popcount(n):
    c = (n & 0x5555555555555555) + ((n >> 1) & 0x5555555555555555)
    c = (c & 0x3333333333333333) + ((c >> 2) & 0x3333333333333333)
    c = (c & 0x0f0f0f0f0f0f0f0f) + ((c >> 4) & 0x0f0f0f0f0f0f0f0f)
    c = (c & 0x00ff00ff00ff00ff) + ((c >> 8) & 0x00ff00ff00ff00ff)
    c = (c & 0x0000ffff0000ffff) + ((c >> 16) & 0x0000ffff0000ffff)
    c = (c & 0x00000000ffffffff) + ((c >> 32) & 0x00000000ffffffff)
    return c


def factorial(N,p):  # 0!~N!(mod p) のリスト
    res = [0]*(N+1)
    res[0] = 1
    for i in range(1,N+1):
        res[i] = (res[i-1]*i) % p
    return res


def factorial_inverse(N,p):  # 0!~N!(mod p) の逆元のリスト
    fac = factorial(N,p)
    res = [0]*(N+1)
    a = pow(fac[-1],p-2,p)
    for i in range(N,-1,-1):
        res[i] = a
        a *= i
        a %= p
    return fac,res


N = I()
B = [0]+LI()
mod = 10**9+7

X = []
for i,b in enumerate(B):
    if b != -1:
        X.append((i,b))

fac,fac_inv = factorial_inverse(30,mod)


def nCr(n,r):
    if n < r:
        return 0
    return (fac[n]*fac_inv[r]*fac_inv[n-r]) % mod


ans = 1
for i in range(len(X)-1):
    i0,b0 = X[i]
    i1,b1 = X[i+1]
    k = i1-i0  # 考える個数

    if b0 & b1 != b0:
        ans = 0
        break

    p0 = popcount(b0)
    p1 = popcount(b1)
    d = p1-p0  # 新しく加わるbitの個数

    a = 0
    for t in range(d+1):
        x = nCr(d,t)*pow(pow(2,p1-t,mod)-1,k,mod)
        if t % 2 == 0:
            a += x
        else:
            a -= x
        a %= mod

    ans *= a
    ans %= mod

print(ans)