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

print(dp[n])