n,m=map(int,input().split())
a = []

mod = 1_000_000_007

dp=[0]*(n+1)

dp[0]=1
dp[1]=1

for _ in range(m):
    s = int(input())
    a.append(s)

    dp[s]=0


for i in range(2,n+1):
    if i in a:
        dp[i] = 0
    else:
        dp[i] = dp[i-1] + dp[i-2]

print(dp[-1]%mod) 
