n, m = map(int, input().split())
a = [0] * m
dp = [1, 1]
x = 0
for i in range(m):
    a[i] = int(input())
if a[0] == 1:
    dp[1] = 0
    x = 1

for i in range(len(a)-1):
    if a[i+1] - a[i] == 1:
        print(0)
        exit(0)


for i in range(2, n+1):
    if i != a[x]:
        dp.append((dp[-1] + dp[-2]) % 1000000007)
    else:
        dp.append(0)
        if x < len(a)-1:
            x += 1
# print(dp)
print(dp[-1])
