import sys
input = sys.stdin.readline

mod=10**9+7

FACT=[1]
for i in range(1,2*10**5+1):
    FACT.append(FACT[-1]*i%mod)

FACT_INV=[pow(FACT[-1],mod-2,mod)]
for i in range(2*10**5,0,-1):
    FACT_INV.append(FACT_INV[-1]*i%mod)

FACT_INV.reverse()

def Combi(a,b):
    if 0<=b<=a:
        return FACT[a]*FACT_INV[b]%mod*FACT_INV[a-b]%mod
    else:
        return 0

N=int(input())
B=list(map(int,input().split()))

ANS=1
now=0
minus=0

for i in range(N):
    if B[i]==-1:
        minus+=1
    else:
        x=B[i]

        if x & now == now:
            k=now.bit_count()
            l=x.bit_count()

            score=0
            rest=l-k

            #print("!",rest)

            for j in range(rest+1):
                if j%2==0:
                    score=score+Combi(rest,j)*pow(pow(2,l-j)-1,minus+1,mod)
                else:
                    score=score-Combi(rest,j)*pow(pow(2,l-j)-1,minus+1,mod)

                #print(score)
                score%=mod

            #print("?",score)

            minus=0
            now=x
            ANS=ANS*score%mod
        else:
            print(0)
            exit()
    

k=now.bit_count()

ANS=ANS*pow(pow(2,k)-1,minus,mod)%mod

print(ANS)