Buggy python submission (verdict: Runtime Error):
from collections import Counter
n = int(input())
lst = [int(i) for i in input().split()]
mod = 10**9 + 7
lst_c = Counter(lst)
lst_c = sorted(lst_c.items(),key = lambda x:x[0])

ideal = []

if n%2!=0:
    ideal.append((0,1))
    for i in range(1,n//2+1):
        ideal.append((2*i,2))
else:
    for i in range(n//2):
        ideal.append((2*i+1,2))

if lst_c != ideal:
    print(0)
else:
    l = len(ideal)
    if n%2!=0:
        l -= 1
    print(2**l　% mod)



Fixed submission:
from collections import Counter
n = int(input())
lst = [int(i) for i in input().split()]
mod = 10**9 + 7
lst_c = Counter(lst)
lst_c = sorted(lst_c.items(),key = lambda x:x[0])

ideal = []

if n%2!=0:
    ideal.append((0,1))
    for i in range(1,n//2+1):
        ideal.append((2*i,2))
else:
    for i in range(n//2):
        ideal.append((2*i+1,2))

if lst_c != ideal:
    print(0)
else:
    l = len(ideal)
    if n%2!=0:
        l -= 1
    print(2**l % mod)

Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
lst = [int(i) for i in input().split()]
mod = 10**9 + 7

flg = True
cnt = 0
ans = 1
if n%2 != 0:
    for i in range(n):
        if i==0:
            if lst.count(0) != 1:
                flg = False
        elif i%2!=0 and lst.count(i)!=0:
            flg = False
        elif i%2==0 and lst.count(i)!=2:
            flg = False
        elif i%2==0 and lst.count(i)==2:
            cnt += 1
    
else:
    for i in range(1,n):
        if i%2==0 and lst.count(i)!=0:
            flg = False
        elif i%2!=0 and lst.count(i)!=2:
            flg = False
        elif i%2!=0 and lst.count(i)==2:
            cnt += 1

if flg:
    for i in range(cnt):
        ans *= 2
        ans %= mod
    print(ans)
    
else:
    print(0)

Fixed submission:
from collections import Counter
n = int(input())
lst = [int(i) for i in input().split()]
mod = 10**9 + 7
lst_c = Counter(lst)
lst_c = sorted(lst_c.items(),key = lambda x:x[0])

ideal = []

if n%2!=0:
    ideal.append((0,1))
    for i in range(1,n//2+1):
        ideal.append((2*i,2))
else:
    for i in range(n//2):
        ideal.append((2*i+1,2))

if lst_c != ideal:
    print(0)
else:
    l = len(ideal)
    if n%2!=0:
        l -= 1
    print(2**l % mod)

Buggy python submission (verdict: Time Limit Exceeded):
n = int(input())
lst = [int(i) for i in input().split()]
mod = 10**9 + 7


flg = True
cnt = 0
if n%2 != 0:
    for i in range(n):
        if i==0:
            if lst.count(0) != 1:
                flg = False
        elif i%2!=0 and lst.count(i)!=0:
            flg = False
        elif i%2==0 and lst.count(i)!=2:
            flg = False
        elif i%2==0 and lst.count(i)==2:
            cnt += 1
    ans = 2 ** cnt
    
else:
    for i in range(1,n):
        if i%2==0 and lst.count(i)!=0:
            flg = False
        elif i%2!=0 and lst.count(i)!=2:
            flg = False
        elif i%2!=0 and lst.count(i)==2:
            cnt += 1
    ans = 2 ** cnt

if flg:
    print(ans % mod)
else:
    print(0)

Fixed submission:
from collections import Counter
n = int(input())
lst = [int(i) for i in input().split()]
mod = 10**9 + 7
lst_c = Counter(lst)
lst_c = sorted(lst_c.items(),key = lambda x:x[0])

ideal = []

if n%2!=0:
    ideal.append((0,1))
    for i in range(1,n//2+1):
        ideal.append((2*i,2))
else:
    for i in range(n//2):
        ideal.append((2*i+1,2))

if lst_c != ideal:
    print(0)
else:
    l = len(ideal)
    if n%2!=0:
        l -= 1
    print(2**l % mod)