Buggy python submission (verdict: Time Limit Exceeded):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
dp = [0 for _ in range(0,N+1)]
dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0
for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if (i-1) not in arr: dp[i] += dp[i-1]
    if (i-2) not in arr: dp[i] += dp[i-2]
print(dp[N] % (10**9 + 7))

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)

Buggy python submission (verdict: Time Limit Exceeded):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]

arr = [-1]+arr+[N+1]
from math import factorial

count = 0
memo = {}
for i in range(0,len(arr)-1):
    start,end = arr[i],arr[i+1]
    span = end - start - 2 # the first step is taken by a certain step (with no choice)
    if span < 0:
        count = 0 # impossible
        break 
    nptn = int(span/2)
    regional_count = 0

    for k in range(0,nptn+1):
        key = '{} {}'.format(span,k)
        if key in memo.keys():
            regional_count += memo[key]
        else:
            val = factorial(span-k) // factorial(k) // factorial(span-2*k)
            regional_count += val
            memo[key] = val
    
    if count == 0:
        count += regional_count
    else:
        count *= regional_count
print(count % 1000000007)

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)

Buggy python submission (verdict: Time Limit Exceeded):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]

arr = [-1]+arr+[N+1]
#from math import factorial
from functools import reduce
count = 0
for i in range(0,len(arr)-1):
    start,end = arr[i],arr[i+1]
    span = end - start - 2 # the first step is taken by a certain step (with no choice)
    if span < 0:
        count = 0 # impossible
        break 
    nptn = int(span/2)
    regional_count = 0

    for k in range(0,nptn+1):
        #regional_count += factorial(span-k) // factorial(k) // factorial(span-2*k)
        mul = lambda a,b: a*b
        regional_count += reduce(mul, range(span-k,k,-1),1) // reduce(mul, range(1,span-2*k+1),1)
    
    if count == 0:
        count += regional_count
    else:
        count *= regional_count
print(count % 1000000007)

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)

Buggy python submission (verdict: Runtime Error):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]

arr = [-1]+arr+[N+1]
from math import factorial
count = 0
for i in range(0,len(arr)-1):
    start,end = arr[i],arr[i+1]
    span = end - start - 2 # the first step is taken by a certain step (with no choice)
    if span < 0:
        count = 0 # impossible
        break 
    nptn = int(span/2)
    regional_count = 0

    for k in range(0,nptn+1):
        #regional_count += factorial(span-k) // factorial(k) // factorial(span-2*k)
        mul = lambda a,b: a*b
        regional_count += reduce(mul, range(span-k,k,-1),1) // reduce(mul, range(1,span-2*k+1),1)
    
    if count == 0:
        count += regional_count
    else:
        count *= regional_count
print(count % 1000000007)

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)

Buggy python submission (verdict: Time Limit Exceeded):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]

arr = [-1]+arr+[N+1]

from operator import mul
from functools import reduce

def factorial(n):
    return reduce(mul, range(n, 0, -1), 1)
  
count = 0

for i in range(0,len(arr)-1):
    start,end = arr[i],arr[i+1]
    span = end - start - 2 # the first step is taken by a certain step (with no choice)
    if span < 0:
        count = 0 # impossible
        break 
    nptn = int(span/2)
    regional_count = 0

    for k in range(0,nptn+1):
        regional_count += factorial(span-k) // factorial(k) // factorial(span-2*k)
    
    if count == 0:
        count += regional_count
    else:
        count *= regional_count
print(count % 1000000007)

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)

Buggy python submission (verdict: Time Limit Exceeded):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]

arr = [-1]+arr+[N+1]
from math import factorial
count = 0
for i in range(0,len(arr)-1):
    start,end = arr[i],arr[i+1]
    span = end - start - 2 # the first step is taken by a certain step (with no choice)
    if span < 0:
        count = 0 # impossible
        break 
    nptn = int(span/2)
    regional_count = 0

    for k in range(0,nptn+1):
        regional_count += factorial(span-k) // factorial(k) // factorial(span-2*k)
    
    if count == 0:
        count += regional_count
    else:
        count *= regional_count
print(count % 1000000007)

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)

Buggy python submission (verdict: Runtime Error):
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]

arr = [-1]+arr+[N+1]
from math import factorial
count = 0
for i in range(0,len(arr)-1):
    start,end = arr[i],arr[i+1]
    span = end - start - 2 # the first step is taken by a certain step (with no choice)
    nptn = int(span/2)
    regional_count = 0
    print(span,nptn)
    for k in range(0,nptn+1):
        print(span,k,factorial(span-k)//factorial(k)//factorial(span-2*k))
        regional_count += factorial(span-k) // factorial(k) // factorial(span-2*k)
    print(regional_count)
    if count == 0:
        count += regional_count
    else:
        count *= regional_count
print(count % 1000000007)

Fixed submission:
N,M = map(int, input().split())
arr = [int(input()) for _ in range(0,M)]
MOD = 10**9 + 7
stairs = [True for _ in range(0,N+1)]
for x in arr:
    stairs[x] = False

dp = [0 for _ in range(0,N+1)]

dp[0] = 1 if 0 not in arr else 0
dp[1] = 1 if 1 not in arr else 0

for i in range(2,N+1):
    if dp[i-1] == 0 and dp[i-2] == 0:
        break
    if stairs[i-1]: dp[i] += dp[i-1]
    if stairs[i-2]: dp[i] += dp[i-2]

    dp[i] %= MOD

print(dp[-1] % MOD)