n,m=map(int,input().split())
step=list(range(2,n+1))
broken=[]
for i in range(m):
    broken+=[int(input())]
mod=10**9+7
dp=[0]*(n+1)
dp[0]=1
if not broken[0]==1:
    dp[1]=1
for i in step:
    if not i in broken:
        dp[i]=(dp[i-1]+dp[i-2])%mod
print(dp[n])