Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
p = 10 ** 9 + 7
if N%2==0:
    B= sorted([2*i-1 for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans=(pow(2,int(N/2))%(10 ** 9 + 7)
    else:
        ans=0
else:
    B= [0]+sorted([2*i for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans=(pow(2,int(N/2))%(10 ** 9 + 7)
    else:
        ans=0
print(int(ans))
 


Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
p = 10 ** 9 + 7
if N%2==0:
    B= sorted([2*i-1 for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans=(pow(2,N/2))%(10 ** 9 + 7)
    else:
        ans=0
else:
    B= [0]+sorted([2*i for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans=(pow(2,N/2))%(10 ** 9 + 7)
    else:
        ans=0
print(int(ans))
 


Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    B= sorted([2*i-1 for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans=(pow(2,N/2))%(10**9+7)
    else:
        ans=0
else:
    B= [0]+sorted([2*i for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans=(pow(2,(N-1)/2))%(10**9+7)
    else:
        ans=0
print(int(ans))

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    B= sorted([2*i-1 for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans0=pow(2,(N/2))
        
        ans=ans0%(10**9+7)
    else:
        ans=0
else:
    B= [0]+sorted([2*i for i in range(1,N//2+1)]*2)
    if sorted(A)==B:
        ans0=pow(2,(N-1)/2)
        ans=ans0%(10**9+7)
    else:
        ans=0
print(int(ans))
 

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    for i in range((N//2)):
        B.append(2*i+1)
        B.append(2*i+1)
    if sorted(A)==B:
        ans0=pow(2,(N/2))
        
        ans=ans0%(10**9+7)
    else:
        ans=0
else:
    B.append(0)
    for i in range(1,((N-1)//2)+1):
        B.append(2*i)
        B.append(2*i)
    if sorted(A)==B:
        ans0=pow(2,(N-1)/2)
        ans=ans0%(10**9+7)
    else:
        ans=0
print(int(ans))
 

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    for i in range((N//2)):
        B.append(2*i+1)
        B.append(2*i+1)
    if sorted(A)==sorted(B):
        ans0=pow(2,(N/2))
        
        ans=ans0%(10**9+7)
    else:
        ans=0
else:
    B.append(0)
    for i in range(1,((N-1)//2)+1):
        B.append(2*i)
        B.append(2*i)
    if sorted(A)==sorted(B):
        ans0=pow(2,(N-1)/2)
        ans=ans0%(10**9+7)
    else:
        ans=0
print(int(ans))
 

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    for i in range((N//2)):
        B.append(2*i+1)
        B.append(2*i+1)
    if sorted(A)==sorted(B):
        ans0=pow(2,(N/2))
        
        ans=ans0%(10**9+7)
    else:
        ans=0
else:
    B.append(0)
    for i in range(1,((N-1)//2)+1):
        B.append(2*i)
        B.append(2*i)
    if sorted(A)==sorted(B):
        ans0=pow(2,(N-1)/2)
        ans=ans0%(10**9+7)
    else:
        ans=0
print(ans)
 

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    for i in range((N//2)):
        B.append(2*i+1)
        B.append(2*i+1)
    if sorted(A)==sorted(B):
        ans0=pow(2,(N/2))
        ans=ans0%(10**9+7)
    else:
        ans=0
else:
    B.append(0)
    for i in range(1,((N-1)//2)+1):
        B.append(2*i)
        B.append(2*i)
    if sorted(A)==sorted(B):
        ans0=pow(2,(N-1)/2)
        ans=ans0%(10**9+7)
    else:
        ans=0
print(int(ans))

        

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)

Buggy python submission (verdict: Runtime Error):
N=int(input())
A=[int(x)for x in input().split()]
B=[]
if N%2==0:
    for i in range((N//2)):
        B.append(2*i+1)
        B.append(2*i+1)
    if sorted(A)==sorted(B):
        ans=(2**(N/2))%(10**9+7)
    else:
        ans=0
else:
    B.append(0)
    for i in range(1,((N-1)//2)+1):
        B.append(2*i)
        B.append(2*i)
    if sorted(A)==sorted(B):
        ans=(2**((N-1)/2))%(10**9+7)
    else:
        ans=0
print(int(ans))

        
    

Fixed submission:
mod = 10**9 + 7
n = int(input())
a = sorted(list(map(int,input().split())))
 
if n % 2 == 0:
  for i in range(n//2):
    if not a[2*i] == a[2*i+1] == 2*i+1:
      print(0)
      exit()
else:
  if a[0] != 0:
    print(0)
    exit()
  for i in range(n//2):
    if not a[2*i+1] == a[2*i+2] == 2*i+2:
      print(0)
      exit()
print(pow(2, n//2) % mod)