n,m = map(int,input().split())


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

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


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

print(dp[n]%1000000007)