N,M = map(int,input().split())
A= set(int(input()) for _ in [0]*M)
mod = 10**9+7
dp = [0]*(N+1)
dp[0] = 1
if not (1 in A):dp[1] = 1
for i in range(2,N+1):
    dp[i] = (dp[i-1]+dp[i-2])%mod
    if i in A:dp[i]=0
print(dp[N])