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