Buggy python submission (verdict: Runtime Error):
n=int(input())
a=list(map(int,input().split()))
a.sort()
if n%2==1:
    if a[0]!=0:
        print(0)
        exit()
    for i in range(n//2):
        if a[2*i+1]!=2*(i+1) or a[2*(i+1)]!=2*(i+1):
            print(0)
            exit()
    print((pow(2,n//2))%(1e9+7))
else:
    for i in range(n//2):
        if a[2*i]!=2*i+1 or a[2*i+1]!=2*i+1:
            print(0)
            exit()
    print((pow(2,n//2))%(1e9+7))

Fixed submission:
N = int(input())
A = list(map(int, input().split()))
A.sort()
if N % 2 == 1:
    if A[0] != 0:
        print(0)
        exit()
    for i in range(N // 2):
        if A[2 * i + 1] != 2 * (i + 1) or A[2 * i + 2] != 2 * (i + 1):
            print(0)
            exit()
    print(pow(2, N // 2) % (10 ** 9 + 7))
else:
    for i in range(N // 2):
        if A[2 * i] != 2 * i + 1 or A[2 * i + 1] != 2 * i + 1:
            print(0)
            exit()
    print((pow(2, N // 2)) % (10 ** 9 + 7))

Buggy python submission (verdict: Runtime Error):
n=int(input())
a=list(map(int,input().split()))
a.sort()
if n%2==1:
    if a[0]!=0:
        print(0)
        exit()
    for i in range(n//2):
        if a[2*i+1]!=2*(i+1) or a[2*(i+1)]!=2*(i+1):
            print(0)
            exit()
    print((pow(2,n//2))%(1e9+7))
else:
    for i in range(n//2):
        if a[2*i]!=2*i+1 or a[2*i+1]!=2*i+1:
            print(0)
            exit()
    print(((pow(2,n//2))%(1e9+7)))

Fixed submission:
N = int(input())
A = list(map(int, input().split()))
A.sort()
if N % 2 == 1:
    if A[0] != 0:
        print(0)
        exit()
    for i in range(N // 2):
        if A[2 * i + 1] != 2 * (i + 1) or A[2 * i + 2] != 2 * (i + 1):
            print(0)
            exit()
    print(pow(2, N // 2) % (10 ** 9 + 7))
else:
    for i in range(N // 2):
        if A[2 * i] != 2 * i + 1 or A[2 * i + 1] != 2 * i + 1:
            print(0)
            exit()
    print((pow(2, N // 2)) % (10 ** 9 + 7))

Buggy python submission (verdict: Runtime Error):
n=int(input())
a=list(map(int,input().split()))
a.sort()
if n%2==1:
    if a[0]!=0:
        print(0)
        exit()
    for i in range(n//2):
        if a[2*i+1]!=2*(i+1) or a[2*(i+1)]!=2*(i+1):
            print(0)
            exit()
    print(int(pow(2,n//2)%(1e9+7)))
else:
    for i in range(n//2):
        if a[2*i]!=2*i+1 or a[2*i+1]!=2*i+1:
            print(0)
            exit()
    print(int(pow(2,n//2)%(1e9+7)))

Fixed submission:
N = int(input())
A = list(map(int, input().split()))
A.sort()
if N % 2 == 1:
    if A[0] != 0:
        print(0)
        exit()
    for i in range(N // 2):
        if A[2 * i + 1] != 2 * (i + 1) or A[2 * i + 2] != 2 * (i + 1):
            print(0)
            exit()
    print(pow(2, N // 2) % (10 ** 9 + 7))
else:
    for i in range(N // 2):
        if A[2 * i] != 2 * i + 1 or A[2 * i + 1] != 2 * i + 1:
            print(0)
            exit()
    print((pow(2, N // 2)) % (10 ** 9 + 7))

Buggy python submission (verdict: Runtime Error):
n=int(input())
a=list(map(int,input().split()))
a.sort()
if n%2==1:
    if a[0]!=0:
        print(0)
        exit()
    for i in range(n//2):
        if a[2*i+1]!=2*(i+1) or a[2*(i+1)]!=2*(i+1):
            print(0)
            exit()
    print(pow(2,n//2)%(1e9+7))
else:
    for i in range(n//2):
        if a[2*i]!=2*i+1 or a[2*i+1]!=2*i+1:
            print(0)
            exit()
    print(pow(2,n//2)%(1e9+7))

Fixed submission:
N = int(input())
A = list(map(int, input().split()))
A.sort()
if N % 2 == 1:
    if A[0] != 0:
        print(0)
        exit()
    for i in range(N // 2):
        if A[2 * i + 1] != 2 * (i + 1) or A[2 * i + 2] != 2 * (i + 1):
            print(0)
            exit()
    print(pow(2, N // 2) % (10 ** 9 + 7))
else:
    for i in range(N // 2):
        if A[2 * i] != 2 * i + 1 or A[2 * i + 1] != 2 * i + 1:
            print(0)
            exit()
    print((pow(2, N // 2)) % (10 ** 9 + 7))

Buggy python submission (verdict: Runtime Error):
n=int(input())
a=list(map(int,input().split()))
ans=1
a.sort()
la=list(set(a))
if n%2==0:
    for i in range(1,n,2):
        if a.count(i)==2:
            ans*=2
            ans%=1e9+7
        else:
            ans=0
            break
else:
    if a[0]==0 and a[1]!=0:
        a=a[1:]
        for i in range(2,n,2):
            if a.count(i)==2:
                ans*=2
                ans%=1e9+7
            else:
                ans=0
                break
    else:
        ans=0
print(int(ans))

Fixed submission:
N = int(input())
A = list(map(int, input().split()))
A.sort()
if N % 2 == 1:
    if A[0] != 0:
        print(0)
        exit()
    for i in range(N // 2):
        if A[2 * i + 1] != 2 * (i + 1) or A[2 * i + 2] != 2 * (i + 1):
            print(0)
            exit()
    print(pow(2, N // 2) % (10 ** 9 + 7))
else:
    for i in range(N // 2):
        if A[2 * i] != 2 * i + 1 or A[2 * i + 1] != 2 * i + 1:
            print(0)
            exit()
    print((pow(2, N // 2)) % (10 ** 9 + 7))