n,m = list(map(int, input("").split()))
a=set([int(input()) for i in range(m)])

print(a)

mod = 10 ** 9 + 7

dp = [0] * (n+2)
dp[1] = 1

for i in range(2,n+2):
    if i-1 not in a:
        dp[i] = dp[i-1] % mod + dp[i-2] % mod
        
print(dp[n+1] % mod)