Buggy python submission (verdict: Runtime Error):
import sys
input = sys.stdin.readline

N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
dp = [0] * N
broke = False
if 1 in a and 2 not in a:
    dp[1] = 1
elif 1 not in a and 2 in a:
    dp[0] = 1
else:
    dp[0] = 1
    dp[1] = 2
if 1 in a and 2 in a:
    print('0')
    broke = True
else:
    for i in range(3,N+1):
        if i-1 in a and i-2 in a:
            print('0')
            broke = True
            break
        elif i-1 in a:
            dp[i-1] = dp[i-3]
        elif i-2 in a:
            dp[i-1] = dp[i-2]
        else:
            dp[i-1] = (dp[i-2] + dp[i-3]) % 1000000007
if broke == False:
    print(dp[N-1])

Fixed submission:
N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
dp = [0] * N
broke = False
if N == 1:
    print('1')
    broke = True
elif 1 in a and 2 not in a:
    dp[1] = 1
elif 1 not in a and 2 in a:
    dp[0] = 1
else:
    dp[0] = 1
    dp[1] = 2
if 1 in a and 2 in a:
    print('0')
    broke = True
else:
    for i in range(3,N+1):
        if i-1 in a and i-2 in a:
            print('0')
            broke = True
            break
        elif i-1 in a:
            dp[i-1] = dp[i-3]
        elif i-2 in a:
            dp[i-1] = dp[i-2]
        else:
            dp[i-1] = (dp[i-2] + dp[i-3]) % 1000000007
if broke == False:
    print(dp[N-1])

Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(100000000000)
input = sys.stdin.readline

N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
mem = [0] * N
def count_steps(n):
    if mem[n-1]:
        return mem[n-1]
    elif n - 1 in a and n - 2 in a:
        return 0
    elif n - 1 in a:
        if n > 2:
            mem[n-1] = count_steps(n-2)
            return mem[n-1]
        else:
            mem[1] = 1
            return 1
    elif n - 2 in a:
        mem[n-1] = count_steps(n-1)
        return mem[n-1]
    elif n == 1:
        mem[0] = 1
        return 1
    elif n == 2:
        mem[1] = 2
        return 2
    else:
        mem[n-1] = (count_steps(n-1) + count_steps(n-2)) % 1000000007
        return mem[n-1]
print(count_steps(N))

Fixed submission:
N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
dp = [0] * N
broke = False
if N == 1:
    print('1')
    broke = True
elif 1 in a and 2 not in a:
    dp[1] = 1
elif 1 not in a and 2 in a:
    dp[0] = 1
else:
    dp[0] = 1
    dp[1] = 2
if 1 in a and 2 in a:
    print('0')
    broke = True
else:
    for i in range(3,N+1):
        if i-1 in a and i-2 in a:
            print('0')
            broke = True
            break
        elif i-1 in a:
            dp[i-1] = dp[i-3]
        elif i-2 in a:
            dp[i-1] = dp[i-2]
        else:
            dp[i-1] = (dp[i-2] + dp[i-3]) % 1000000007
if broke == False:
    print(dp[N-1])

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(1000000000)
input = sys.stdin.readline

N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
mem = [0] * N
def count_steps(n):
    if mem[n-1]:
        return mem[n-1]
    elif n - 1 in a and n - 2 in a:
        return 0
    elif n - 1 in a:
        if n > 2:
            mem[n-1] = count_steps(n-2)
            return mem[n-1]
        else:
            mem[1] = 1
            return 1
    elif n - 2 in a:
        mem[n-1] = count_steps(n-1)
        return mem[n-1]
    elif n == 1:
        mem[0] = 1
        return 1
    elif n == 2:
        mem[1] = 2
        return 2
    else:
        mem[n-1] = (count_steps(n-1) + count_steps(n-2)) % 1000000007
        return mem[n-1]
print(count_steps(N))

Fixed submission:
N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
dp = [0] * N
broke = False
if N == 1:
    print('1')
    broke = True
elif 1 in a and 2 not in a:
    dp[1] = 1
elif 1 not in a and 2 in a:
    dp[0] = 1
else:
    dp[0] = 1
    dp[1] = 2
if 1 in a and 2 in a:
    print('0')
    broke = True
else:
    for i in range(3,N+1):
        if i-1 in a and i-2 in a:
            print('0')
            broke = True
            break
        elif i-1 in a:
            dp[i-1] = dp[i-3]
        elif i-2 in a:
            dp[i-1] = dp[i-2]
        else:
            dp[i-1] = (dp[i-2] + dp[i-3]) % 1000000007
if broke == False:
    print(dp[N-1])

Buggy python submission (verdict: Time Limit Exceeded):
import sys
sys.setrecursionlimit(1000000000)
N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
mem = [0] * N
def count_steps(n):
    if mem[n-1]:
        return mem[n-1]
    elif n == 1:
        if 1 in a:
            return 0
        else:
            mem[0] = 1
            return 1
    elif n == 2:
        if 1 in a:
            mem[1] = 1
            return 1
        else:
            mem[1] = 2
            return 2
    elif n - 1 in a and n - 2 in a:
        return 0
    elif n - 1 in a:
        mem[n-1] = count_steps(n-2)
        return mem[n-1]
    elif n - 2 in a:
        mem[n-1] = count_steps(n-1)
        return mem[n-1]
    else:
        mem[n-1] = (count_steps(n-1) + count_steps(n-2)) % 1000000007
        return mem[n-1]
print(count_steps(N))

Fixed submission:
N,M = (int(x) for x in input().split())
a = set(int(input()) for _ in range(M))
dp = [0] * N
broke = False
if N == 1:
    print('1')
    broke = True
elif 1 in a and 2 not in a:
    dp[1] = 1
elif 1 not in a and 2 in a:
    dp[0] = 1
else:
    dp[0] = 1
    dp[1] = 2
if 1 in a and 2 in a:
    print('0')
    broke = True
else:
    for i in range(3,N+1):
        if i-1 in a and i-2 in a:
            print('0')
            broke = True
            break
        elif i-1 in a:
            dp[i-1] = dp[i-3]
        elif i-2 in a:
            dp[i-1] = dp[i-2]
        else:
            dp[i-1] = (dp[i-2] + dp[i-3]) % 1000000007
if broke == False:
    print(dp[N-1])