n=int(input())
a=list(map(int,input().split()))
prev=0
count=0
MOD=10**9+7
factorials=[1]
temp=1
s=10**5
for i in range(1,s+1):
  temp=(temp*i)%MOD
  factorials.append(temp)
inverses=[]
for i in range(s+1):
  inverses.append(pow(factorials[i],MOD-2,MOD))
ans=1
for _ in range(n):
  count+=1
  if a[_]!=-1:
    bitcount1=0
    bitcount2=0
    fail=0
    for i in range(30):
      if prev&1<<i and not a[_]&1<<i:
        fail=1
      elif prev&1<<i:
        bitcount2+=1
      elif a[_]&1<<i:
        bitcount1+=1
    if fail:
      print(0)
      exit()
    tmp0=0
    for i in range(count+1):
      tmp=pow(-1,count-i)
      tmp=(tmp*factorials[count]*inverses[i]*inverses[count-i])%MOD
      tmp2=1
      for j in range(bitcount1):
        tmp2=(tmp2*(pow(2,i,MOD)-1))%MOD
      tmp0=(tmp0+tmp*tmp2*pow(2,bitcount2*i,MOD))%MOD
    ans=(ans*tmp0)%MOD

    count=0
    prev=a[_]
print(ans)