Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin/env python3
import sys
sys.setrecursionlimit(10000000)
INF = 1<<32

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    dp = [0] *(N+2)
    ckc = [True] * (N+2)
    for i in a:
        ckc[i] = False

    def f(n: int):
        if(dp[n] != 0):
            return dp[n]

        if n <= 0:
            dp[n] = 0
        else:
            if not ckc[n-1] and not ckc[n-2]:
                dp[n] = 0
            elif not ckc[n-1]:
                dp[n] = f(n-2) % MOD
            elif not ckc[n-2]:
                dp[n] = f(n-1) % MOD
            else:
                dp[n] = (f(n-1) + f(n-2)) % MOD
            
        return dp[n]

    dp[0] = 1
    f(N)
    print(dp[N])
    # print(dp)

    return



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [int(next(tokens)) for _ in range(M)]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys
sys.setrecursionlimit(10000)
INF = 1<<32

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    dp = [0] *(N+2)
    ckc = [True] * (N+2)
    for i in a:
        ckc[i] = False

    def f(n: int):
        if(dp[n] != 0):
            return dp[n]

        if n <= 0:
            dp[n] = 0
        else:
            if not ckc[n-1] and not ckc[n-2]:
                dp[n] = 0
            elif not ckc[n-1]:
                dp[n] = f(n-2) % MOD
            elif not ckc[n-2]:
                dp[n] = f(n-1) % MOD
            else:
                dp[n] = (f(n-1) + f(n-2)) % MOD
            
        return dp[n]

    dp[0] = 1
    f(N)
    print(dp[N])
    # print(dp)

    return



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [int(next(tokens)) for _ in range(M)]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys
sys.setrecursionlimit(10000)
INF = 1<<32

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    dp = [0] *(N+2)

    def f(n: int):
        if(dp[n] != 0):
            return dp[n]

        if n <= 0:
            dp[n] = 0
        else:
            if n-1 in a and n-2 in a:
                dp[n] = 0
            elif n-1 in a:
                dp[n] = f(n-2) % MOD
            elif n-2 in a:
                dp[n] = f(n-1) % MOD
            else:
                dp[n] = (f(n-1) + f(n-2)) % MOD
            
        return dp[n]

    dp[0] = 1
    f(N)
    print(dp[N])
    # print(dp)

    return



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [int(next(tokens)) for _ in range(M)]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys
sys.setrecursionlimit(10000)
INF = 1<<32

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    dp = [0] *(N+2)

    def f(n: int):
        if(dp[n] != 0):
            return dp[n]

        if n <= 0:
            dp[n] = 0
        else:
            if n-1 in a and n-2 in a:
                dp[n] = 0
            elif n-1 in a:
                dp[n] = f(n-2) % MOD
            elif n-2 in a:
                dp[n] = f(n-1) % MOD
            else:
                dp[n] = (f(n-1) + f(n-2)) % MOD
            
        return dp[n]

    dp[0] = 1
    f(N)
    print(dp[N])
    # print(dp)

    return



def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [int(next(tokens)) for _ in range(M)]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    l = [a[i+1]-a[i] for i in range(M-1)]
    if(len(l) and min(l)<=1):
        print(0)
        exit()

    dp = [1] * (N+1)
    dp[1] = 1
    dp[2] = 2
    x = 0
    
    for i in range(2,N+1):
        if(a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a)):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    l = [a[i+1]-a[i] for i in range(M-1)]
    if(len(l) and min(l)<=1):
        print(0)
        exit()

    dp = [1] * (N+1)
    dp[1] = 1
    dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()

Buggy python submission (verdict: Runtime Error):
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    l = [a[i+1]-a[i] for i in range(M-1)]
    if(len(l) and min(l)<=1):
        print(0)
        exit()

    dp = [1] * (N+1)
    dp[1] = 1
    dp[2] = 2
    x = 0
    
    for i in range(2,N+1):
        if(a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()


Fixed submission:
#!/usr/bin/env python3
import sys

MOD = 1000000007  # type: int

def solve(N: int, M: int, a: "List[int]"):
    if(len(a) >= 2):
        l = [a[i+1]-a[i] for i in range(M-1)]
        if(len(l) and min(l)<=1):
            print(0)
            exit()

    dp = [1] * (N+1)
    dp[1] = 1
    if(N >= 2):
        dp[2] = 2
    x = 0
    # if(M == 0):
    #     for i in range(2,N+1)
    
    for i in range(2,N+1):
        if(len(a) and a[x] == i-1):
            dp[i] = dp[i-2] % MOD
            # x = min(x+1,M-1)
        elif(len(a) and a[x] == i-2):
            dp[i] = dp[i-1] % MOD
            x = min(x+1,M-1)
        else:
            dp[i] = (dp[i-1] + dp[i-2]) % MOD
    
    print(dp[N])
    
    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    M = int(next(tokens))  # type: int
    a = [ int(next(tokens)) for _ in range(M) ]  # type: "List[int]"
    solve(N, M, a)

if __name__ == '__main__':
    main()