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