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