import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = 10**16
# md = 998244353
md = 10**9+7

def cal(d,m):
    res=0
    for k in range(d+1):
        if k&1:
            res-=pow(2,m*(d-k),md)
        else:
            res+=pow(2,m*(d-k),md)
        res%=md

popcnt=lambda x:bin(x).count("1")

n=II()
bb=LI()
pi=-1
pb=0
ans=1
for i,b in enumerate(bb):
    if pb&b!=pb:
        print(0)
        exit()
    if b==-1:continue
    f=popcnt(pb&b)
    c=popcnt(pb^b)
    ans*=cal(c,i-pi)
    ans%=md
    pi,pb=i,b
    
print(ans)