Buggy python submission (verdict: Runtime Error):
def cmb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result

result = 0

if M == 0:
    for i in range(math.floor((N-1)/2) + 1):
        result += cmb(N - List[M-1]-1-i,i) 
    result = result % 1000000007 
    print(result)

else:
    for i in range(math.floor((List[0]-1)/2) + 1):
        result += cmb(List[0]-1-i,i) 
            
    for i in range(M-1):
        if List[i+1] - List[i] == 1:
            result = 0
            break
        else:
            tmp = 0
            for j in range(math.floor((List[i+1]-List[i]-2)/2) + 1):
                tmp += cmb(List[i+1]-List[i]-2-j,j)
            result = result * tmp

    tmp = 0
    for i in range(math.floor((N - List[M-1]-1)/2) + 1):
        tmp += cmb(N - List[M-1]-1-i,i) 

    result = result * tmp
    result = result % 1000000007 
    print(result)
    
    

Fixed submission:
N, M = map(int, input().split())
a = [int(input()) for i in range(M)]
a.append(-1)

dp = [0 for i in range(N + 1)]
dp[0] = 1
point = 0
if a[point] == 1:
    dp[1] = 0
    point += 1
else:
    dp[1] = 1
for i in range(2, N + 1):
    if i == a[point]:
        dp[i] = 0
        point += 1
    else:
        dp[i] = (dp[i - 2] + dp[i - 1]) % (10 ** 9 + 7)
print(dp[N])

Buggy python submission (verdict: Runtime Error):
import math

def cmb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result

result = 0

N, M = map(int,input().split())

if M == 0:
    for i in range(math.floor((N-1)/2) + 1):
        result += cmb(N - List[M-1]-1-i,i) 
    result = result % 1000000007 
    print(result)

else:
    List = [int(input()) for i in range(M)]
    
    for i in range(math.floor((List[0]-1)/2) + 1):
        result += cmb(List[0]-1-i,i) 
            
    for i in range(M-1):
        if List[i+1] - List[i] == 1:
            result = 0
            break
        else:
            tmp = 0
            for j in range(math.floor((List[i+1]-List[i]-2)/2) + 1):
                tmp += cmb(List[i+1]-List[i]-2-j,j)
            result = result * tmp

    tmp = 0
    for i in range(math.floor((N - List[M-1]-1)/2) + 1):
        tmp += cmb(N - List[M-1]-1-i,i) 

    result = result * tmp
    result = result % 1000000007 
    print(result)

Fixed submission:
N, M = map(int, input().split())
a = [int(input()) for i in range(M)]
a.append(-1)

dp = [0 for i in range(N + 1)]
dp[0] = 1
point = 0
if a[point] == 1:
    dp[1] = 0
    point += 1
else:
    dp[1] = 1
for i in range(2, N + 1):
    if i == a[point]:
        dp[i] = 0
        point += 1
    else:
        dp[i] = (dp[i - 2] + dp[i - 1]) % (10 ** 9 + 7)
print(dp[N])

Buggy python submission (verdict: Runtime Error):
N, M = map(int,input().split())
List = [int(input()) for i in range(M)]

import math

def cmb(n, r):
    if n - r < r: r = n - r
    if r == 0: return 1
    if r == 1: return n

    numerator = [n - r + k + 1 for k in range(r)]
    denominator = [k + 1 for k in range(r)]

    for p in range(2,r+1):
        pivot = denominator[p - 1]
        if pivot > 1:
            offset = (n - r) % p
            for k in range(p-1,r,p):
                numerator[k - offset] /= pivot
                denominator[k] /= pivot

    result = 1
    for k in range(r):
        if numerator[k] > 1:
            result *= int(numerator[k])

    return result

result = 0

if M == 0:
    for i in range(math.floor((N-1)/2) + 1):
        result += cmb(N - List[M-1]-1-i,i) 
    result = result % 1000000007 
    print(result)

else:
    for i in range(math.floor((List[0]-1)/2) + 1):
        result += cmb(List[0]-1-i,i) 
            
    for i in range(M-1):
        if List[i+1] - List[i] == 1:
            result = 0
            break
        else:
            tmp = 0
            for j in range(math.floor((List[i+1]-List[i]-2)/2) + 1):
                tmp += cmb(List[i+1]-List[i]-2-j,j)
            result = result * tmp

    tmp = 0
    for i in range(math.floor((N - List[M-1]-1)/2) + 1):
        tmp += cmb(N - List[M-1]-1-i,i) 

    result = result * tmp
    result = result % 1000000007 
    print(result)
    
    

Fixed submission:
N, M = map(int, input().split())
a = [int(input()) for i in range(M)]
a.append(-1)

dp = [0 for i in range(N + 1)]
dp[0] = 1
point = 0
if a[point] == 1:
    dp[1] = 0
    point += 1
else:
    dp[1] = 1
for i in range(2, N + 1):
    if i == a[point]:
        dp[i] = 0
        point += 1
    else:
        dp[i] = (dp[i - 2] + dp[i - 1]) % (10 ** 9 + 7)
print(dp[N])