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

mod=10**9+7
dp=[0]*(n+1)
dp[0]=1
j=0
for i in range(1,n+1):
    if i == a[j]:
        dp[i]=0
        j=min(m-1,j+1)
    else:
        dp[i]=(dp[i-2]+dp[i-1])%mod
print(dp[-1])
