N,M=map(int, input().split())
A = [int(input()) for i in range(M)]

mod=10**9+7
dp=[0]*(N+1)
dp[0]=1
for i in range(1,N+1):
    if i in A:
        continue
    if i==1:
        dp[1]=dp[0]
        continue
    dp[i]=dp[i-1]+dp[i-2]
    dp[i]%=mod
print(dp[N])