n,m=map(int,input().split())
a=[]
for i in range(m):
    a.append(int(input()))
dp=[0]*(n+1)
if 1 in a:
    dp[1]=0
dp[0]=1
mod=10**9+7
for i in range(2,n+1):
    if i in a:
        continue
    dp[i]=dp[i-1]+dp[i-2]
print(dp[-1]%mod)