mod = 10**9+7
n,m = map(int,input().split())

dp = [0]*(n+2)
dp[0] = 1

for i in range(m):
    dp[int(input())] = -1

for i in range(m):
    if dp[i] != -1:
        if dp[i+1] != -1:
            dp[i+1] += dp[i]
        if dp[i+2] != -1:
            dp[i+2] += dp[i]

print(dp[n]%mod)