n,m=map(int,input().split())
a=[int(input()) for _ in range(m)]
mod=10**9+7

dp=[0]*(n+1)
dp[0]=1
if 1 not in a:
      dp[1]=1
for i in range(2,len(dp)):
      if i not in a:
            dp[i]=dp[i-1]+dp[i-2]
      
print(dp[-1]%mod)