Buggy python submission (verdict: Runtime Error):
from collections import Counter

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

count = Counter(Alist)
res = 1
if N % 2 ==0:
    for i in range(1,N,2):
        if count[i] != 2:
            print(0)
            exit()
else:
    if count[0] != 1:
        print(0)
        exit()
    else:
        for i in range(2,N,2):
            if count[i] != 2
                print(0)
                exit()
print(2**(N//2) % (10**9+7))

Fixed submission:
from collections import Counter

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

count = Counter(Alist)
res = 1
if N % 2 ==0:
    for i in range(1,N,2):
        if count[i] != 2:
            print(0)
            exit()
else:
    if count[0] != 1:
        print(0)
        exit()
    else:
        for i in range(2,N,2):
            if count[i] != 2:
                print(0)
                exit()
print(2**(N//2) % (10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
N= int(input())
Alist = list(map(int, input().split())) 
res = 1
if N % 2 ==0:
    for i in range(0,N//2):
        res = res*2 % (10**9+7)
        if Alist.count(2*i+1) != 2:
            print(0)
            exit()

    print(res)

else:
    if Alist.count(0) != 1:
        print(0)
        exit()
    else:
        for i in range(1,(N+1)//2):
            res = res*2 % (10**9+7)
            if Alist.count(2*i) != 2:
                print(0)
                exit()
    print(res)

Fixed submission:
from collections import Counter

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

count = Counter(Alist)
res = 1
if N % 2 ==0:
    for i in range(1,N,2):
        if count[i] != 2:
            print(0)
            exit()
else:
    if count[0] != 1:
        print(0)
        exit()
    else:
        for i in range(2,N,2):
            if count[i] != 2:
                print(0)
                exit()
print(2**(N//2) % (10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
N= int(input())
Alist = list(map(int, input().split())) 
res = 1
if N % 2 ==0:
    for i in range(0,N//2):
        res = res*2 % (10**9+7)
        if Alist.count(2*i+1) != 2:
            print(0)
            exit()

    print(res)

elif N % 2 ==1:
    if Alist.count(0) != 1:
        print(0)
        exit()
    else:
        for i in range(1,(N+1)//2):
            res = res*2 % (10**9+7)
            if Alist.count(2*i) != 2:
                print(0)
                exit()
    print(res)

Fixed submission:
from collections import Counter

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

count = Counter(Alist)
res = 1
if N % 2 ==0:
    for i in range(1,N,2):
        if count[i] != 2:
            print(0)
            exit()
else:
    if count[0] != 1:
        print(0)
        exit()
    else:
        for i in range(2,N,2):
            if count[i] != 2:
                print(0)
                exit()
print(2**(N//2) % (10**9+7))

Buggy python submission (verdict: Time Limit Exceeded):
N= int(input())
Alist = list(map(int, input().split())) 
res = 1
if N % 2 ==0:
    for i in range(0,N//2):
        if Alist.count(2*i+1) != 2:
            print(0)
            exit()
    for j in range(1,N//2+1):
        res = res*2 % (10**9+7)
    print(res)

elif N % 2 ==1:
    if Alist.count(0) != 1:
        print(0)
        exit()
    else:
        for i in range(1,(N+1)//2):
            if Alist.count(2*i) != 2:
                print(0)
                exit()
    for j in range(1,(N+1)//2):
        res = res*2 % (10**9+7)
    print(res)

Fixed submission:
from collections import Counter

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

count = Counter(Alist)
res = 1
if N % 2 ==0:
    for i in range(1,N,2):
        if count[i] != 2:
            print(0)
            exit()
else:
    if count[0] != 1:
        print(0)
        exit()
    else:
        for i in range(2,N,2):
            if count[i] != 2:
                print(0)
                exit()
print(2**(N//2) % (10**9+7))