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