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,n+1):
    if i in a :
        continue
    else:
        dp[i]= dp[i-1] + dp[i-2]
        dp[i]%= mod


print(dp[n])