n,m=map(int,input().split())
mod=10**9+7

    
dp=[0]*(n+1)
dp[0]=1

a=[int(input()) for i 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[-1])
