n,m = map(int,input().split())
dp = [0] * (n+1)

mod = 10**9 + 7
for i in range(m):
    dp[int(input())] = -1 # 壊れているので、-1としておこう?

dp[0] = 0 # 0段目にいるとしよう
# 1段目が行けなかったら...?
dp[1] = 1 if dp[1] != -1 else -1 # 1段目にいく方法は1通り?
dp[2] = 2 if dp[1] != -1 else (1 if dp[2] != -1 else -1) # 2段目に行く方法は2通り?
for i in range(3,n+1):
    if dp[i] != -1 and dp[i-1] != -1:
        dp[i] += dp[i-1]
        dp[i] %= mod
    if i > 1:
        if dp[i] != -1 and dp[i-2] != -1:
            dp[i] += dp[i-2]
            dp[i] %= mod
print(dp[n]%mod)
