N,M=map(int, input().split())
a=set([int(input()) for i in range(M)])
dp=[0]*(N+1)
dp[0]=1
dp[1]=1
for i in range(1, N+1):
    dp[i]=(dp[i-1]+dp[i-2])%(10**9+7)
    if i in a:
        dp[i]=0
print(dp[N])