Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
a = []
for _ in range(m):
    a.append(int(input()))


def count_steps(NN):

    steps = [0] * (NN + 3)
    steps[1] = 1
    steps[2] = 2
    for i in range(3, NN + 1):
        steps[i] = steps[i - 1] + steps[i - 2]
    return steps[NN]

if a[0] == 1:
    ans = 1
else:
    ans = count_steps(a[0]-1)

for i in range(1, len(a)):
    temp = a[i]-a[i-1]-2
    if temp < 0:
        ans = 0
    elif temp==0:
        ans *= 1
    else:
        ans *= count_steps(temp)

temp = n-a[-1]-1
if temp>0:
    ans *= count_steps(temp)
print(ans%1000000007)

Fixed submission:
n, m = map(int, input().split())
a = []
for _ in range(m):
    a.append(int(input()))


def count_steps(NN):

    steps = [0] * (NN + 3)
    steps[1] = 1
    steps[2] = 2
    for i in range(3, NN + 1):
        steps[i] = steps[i - 1] + steps[i - 2]
    return steps[NN]

if m == 0:
    ans = count_steps(n)
else:
    if a[0] == 1:
        ans = 1
    else:
        ans = count_steps(a[0] - 1)

    for i in range(1, len(a)):
        temp = a[i] - a[i - 1] - 2
        if temp < 0:
            ans = 0
        elif temp == 0:
            ans *= 1
        else:
            ans *= count_steps(temp)

    temp = n - a[-1] - 1
    if temp > 0:
        ans *= count_steps(temp)
print(ans%1000000007)

Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
a = []
for _ in range(m):
    a.append(int(input()))


def count_steps(NN):

    steps = [0] * (NN + 3)
    steps[1] = 1
    steps[2] = 2
    for i in range(3, NN + 1):
        steps[i] = steps[i - 1] + steps[i - 2]
    return steps[NN]

if a[0] == 1:
    ans = 1
else:
    ans = count_steps(a[0]-1)

for i in range(1, len(a)):
    temp = a[i]-a[i-1]-2
    if temp < 0:
        ans = 0
    elif temp==0:
        ans *= 1
    else:
        ans *= count_steps(temp)

ans *= count_steps(n-a[-1]-1)
print(ans%1000000007)

Fixed submission:
n, m = map(int, input().split())
a = []
for _ in range(m):
    a.append(int(input()))


def count_steps(NN):

    steps = [0] * (NN + 3)
    steps[1] = 1
    steps[2] = 2
    for i in range(3, NN + 1):
        steps[i] = steps[i - 1] + steps[i - 2]
    return steps[NN]

if m == 0:
    ans = count_steps(n)
else:
    if a[0] == 1:
        ans = 1
    else:
        ans = count_steps(a[0] - 1)

    for i in range(1, len(a)):
        temp = a[i] - a[i - 1] - 2
        if temp < 0:
            ans = 0
        elif temp == 0:
            ans *= 1
        else:
            ans *= count_steps(temp)

    temp = n - a[-1] - 1
    if temp > 0:
        ans *= count_steps(temp)
print(ans%1000000007)

Buggy python submission (verdict: Runtime Error):
n, m = map(int, input().split())
a = []
for _ in range(m):
    a.append(int(input()))


def count_steps(NN):
    NN -= 1
    steps = [0] * (NN + 3)
    steps[1] = 1
    steps[2] = 2
    for i in range(3, NN + 1):
        steps[i] = steps[i - 1] + steps[i - 2]
    return steps[NN]

if a[0] == 1:
    ans = 1
else:
    ans = count_steps(a[0])

for i in range(1, len(a)):
    ans *= count_steps(a[i]-a[i-1]-1)
ans *= count_steps(n-a[-1])
print(ans%1000000007)

Fixed submission:
n, m = map(int, input().split())
a = []
for _ in range(m):
    a.append(int(input()))


def count_steps(NN):

    steps = [0] * (NN + 3)
    steps[1] = 1
    steps[2] = 2
    for i in range(3, NN + 1):
        steps[i] = steps[i - 1] + steps[i - 2]
    return steps[NN]

if m == 0:
    ans = count_steps(n)
else:
    if a[0] == 1:
        ans = 1
    else:
        ans = count_steps(a[0] - 1)

    for i in range(1, len(a)):
        temp = a[i] - a[i - 1] - 2
        if temp < 0:
            ans = 0
        elif temp == 0:
            ans *= 1
        else:
            ans *= count_steps(temp)

    temp = n - a[-1] - 1
    if temp > 0:
        ans *= count_steps(temp)
print(ans%1000000007)